• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
Life Around The Table
  • Home
  • Recipe Index
  • Sides and Appetizers
  • About Me
  • eBooks
  • Subscribe
menu icon
go to homepage
  • Home
  • Recipe Index
  • Sides and Appetizers
  • About Me
  • eBooks
  • Subscribe
    • Email
    • Facebook
    • Instagram
    • Pinterest
  • subscribe
    search icon
    Homepage link
    • Home
    • Recipe Index
    • Sides and Appetizers
    • About Me
    • eBooks
    • Subscribe
    • Email
    • Facebook
    • Instagram
    • Pinterest
  • ×
    Home » Recipes » Recipes

    Fermented Onions (Lacto Fermentation Method)

    Published: Mar 11, 2022 · Modified: Feb 19, 2023 by Christy Faber · 20 Comments

    Love this recipe? Share it!

    Jump to Recipe

    Fermented onions are made using brine (water and salt) and time. Fermenting onions at home is easy and totally worth the effort. The best part is that the health benefits are enormous! Fermented onions are more digestible and higher in nutrients than raw, fresh onions. Fermented vegetables are rich in enzymes and probiotics.

    Although there are many health reasons to incorporate fermented foods into your kitchen, many people choose to ferment foods for the delicious flavour. Fermenting onions makes them less pungent but creates a fresh, tangy and sour condiment that is perfect for topping dishes such as stir-fries or salads. I love having fermented onions or fermented leeks in my fridge to add an extra boost of nutrition to my lunch bowls.

    It took me a long time to work up the courage to try lacto-fermenting vegetables in my home kitchen. I was convinced of the health benefits and it was painful spending so much of my grocery budget on expensive jars of fermented vegetables from the health food store when I knew I could do it for a fraction of the cost at home. But I was nervous that I wouldn’t know if the fermentation had gone wrong.

    After a lot of reading, experimentation and watching videos including this one by Joshua Weissman, I now feel super confident when fermenting vegetables. Here are some of my tips for a successful fermentation.

    Tips for Successful Fermentation

    • Use a kitchen scale. This method ensures that you’re using enough salt and increases the chance of a successful fermentation. 
    • Keep the onions totally submerged. It’s important that the item you’re fermenting is kept in an oxygen free environment. Peek at your fermenting jar once a day to check that everything is still submerged.
    • Discard your ferment if you see black or brightly coloured molds.
    • Discard your ferment if it smells really awful. If you’re not sure what I mean by this, believe me you’ll know.
    • Keep your ferments out of direct sunlight.

    Ways To Use Fermented Onions

    • Top burgers or sausage. 
    • Mix into a Greek salad.
    • Use as a condiment to add acidity and brightness to a dish.
    • Add colour and nutrition to your plate.
    • Top scrambled eggs or an omelette.

    How to Ferment Onions

    1. Choose a mason jar that is the appropriate size to fit the sliced onion. I used a 16 oz wide mouth style mason jar. Place the mason jar on your kitchen scale and press tare to zero out the weight of the jar.
    2.  Fit the sliced onion into the mason jar and pour in enough water to cover the onions. Take note of the total weight in grams of the onion and water combined. To determine the amount of salt you need to add in grams, multiply that number by .02.
    3. For example If the weight of the onion and water combined is 800 grams then you will multiply 800 by .02 and get 16. I would add 16 grams of salt to my jar.
    4. Tare the scale again and add the amount of salt in grams that you determined in the above step. Put on the lid and shake well to dissolve the salt.
    5. It’s very important to keep the onions submerged. To do this you can use fermentation weights, pinch bowls, small mason jar or a plastic sandwich bag filled with a little water. (See photos for examples.)
    6. Leave your ferment at room temperature away from sunlight for 4-7 days. Check it once a day to make sure the onions are submerged. Open the lid slightly on a daily basis to prevent pressure from building up in the jar. Close it again tightly.
    7. Once your fermented onions have reached the desired flavour, place the jar in the fridge. This will halt the fermentation process. Your fermented onions will now keep for a very long time. Enjoy!

    Frequently Asked Questions

    What is lacto-fermentation?

    Lacto-fermentation is the process of lactic-acid-producing bacteria breaking down the sugars or glucose in fruits, vegetables, or other foods into lactic acid. It does this in an environment free of oxygen. 
    You can lacto-ferment many different vegetables or foods including meat or dairy. Some examples of popular lacto-fermented foods would be yogurt, sourdough bread, sauerkraut and cucumbers. 

    Does lacto fermentation produce alcohol?

    Yes, lacto fermentation can produce trace amounts of alcohol. This happens as the bacteria breaks sugar down into lactic acid. Typically the alcohol content is very minute but the longer a ferment is left out at room temperature, the more risk for the alcohol content to increase.

    What salt is best for lacto fermentation?

    The best salt to use for lacto fermentation would be either unrefined sea salt or pickling salt.  Avoid using an iodized salt like table salt or a heavily refined salt as this can affect your ferment.

    More Recipes to Enjoy Around the Table

    Spelt Flour Pancakes
    Spelt Flour Pancakes are a super tasty and healthy way to start the day! Made with simple, wholesome ingredients, these pancakes are a delicious way to incorporate spelt flour in your recipe repertoire.

    Einkorn Flour Banana Bread

    This banana bread recipe is made with nutritious and delicious Einkorn flour. This is an incredibly tender and moist banana bread recipe and Einkorn flour lends a wonderful nutty flavour.  

    Buckwheat Flour Banana Muffins

    Buckwheat flour lends a nutty flavour that compliments these double chocolate banana muffins so well. Oat flour adds a lightness, making the muffins more tender. These muffins are perfect for breakfast or a snack!

    Tools You May Need For This Recipe

    Kitchen Scale

    Mason Jar

    Fermentation Weights

    Pickling Salt

    Noma Guide to Fermentation

    Fermented Onions

    finished product of the fermented onions in a mason jar on a counter top

    Lacto Fermented Onions

    Christy Faber
    Fermented onions are made using brine (water and salt) and time. Fermenting onions is easy and worth the effort. The best part is that the health benefits are enormous! Fermented onions are more digestible and higher in nutrients than raw, fresh onions. Fermented vegetables are rich in enzymes and probiotics.
    5 from 10 votes
    Print Recipe Pin Recipe SaveSaved!
    Prep Time 10 minutes mins
    Fermenation 4 days d
    Total Time 4 days d 10 minutes mins
    Course Appetizer, Side Dish, Snack
    Cuisine American
    Servings 6 people
    Calories 10 kcal

    Equipment

    • kitchen scale
    • fermentation weight or plastic sandwich bag
    • mason jar (16oz)

    Ingredients
      

    • 1 large onion
    • distilled water weight to be determined
    • sea salt or pickling salt weight to be determined

    Instructions
     

    • Choose a mason jar that is the appropriate size to fit the sliced onion. I used a 16 oz wide mouth style mason jar. Place the mason jar on your kitchen scale and press tare to zero out the weight of the jar.
    •  Fit the sliced onion into the mason jar and pour in enough water to cover the onions. Take note of the total weight in grams of the onion and water combined. To determine the amount of salt you need to add in grams, multiply that number by .02.
    • For example If the weight of the onion and water combined is 800 grams then you will multiply 800 by .02 and get 16. I would add 16 grams of salt to my jar.
    • Tare the scale again and add the amount of salt in grams that you determined in the above step. Put on the lid and shake well to dissolve the salt.
    • It’s very important to keep the onions submerged. To do this you can use fermentation weights, pinch bowls, small mason jar or a plastic sandwich bag filled with a little water. (See photos for examples.)
    • Leave your ferment at room temperature away from sunlight for 4-7 days. Check it once a day to make sure the onions are submerged. Open the lid slightly on a daily basis to prevent pressure from building up in the jar. Close it again tightly.
    • Once your fermented onions have reached the desired flavour, place the jar in the fridge. This will halt the fermentation process. Your fermented onions will now keep for a very long time. Enjoy!

    Notes

    Recipe variations:  Get creative.  Try adding garlic or peppercorns, dill or other herbs to your ferment.

    Nutrition

    Calories: 10kcal
    Tried this recipe?Let us know how it was!

    If you make this recipe please leave a comment and give this recipe a rating! I aim to respond to every single comment. I am so grateful when you trust me and try one of my recipe creations in your own kitchen. I love to hear how it went!  Let’s connect on Instagram and tag me in your food pics!

    ‘Til next time,

    Christy

    More Recipes

    • Balsamic Green Beans with Crispy Bread Crumbs
    • Kale Parmesan Farro Soup
    • One-Pot Beef and Farro Soup
    • Lemon Panna Cotta

    Reader Interactions

    Comments

    1. Redeemed Acres says

      January 28, 2025 at 11:53 am

      I want to encourage people to not use plastic bags or Tupperware with onions especially as onions are a naturally puller. They will suck up all the micro plastics and that's what you will be eating. Then you can look into micro plastics effects on your body and health. Remember healthy foods are only as healthy as the quality of foods and tools you use. Mason fermenting kits are the best the weights are made out of the same glass as their jars. They will last forever, super affordable, and easy to use and reuse over and over.

      Reply
    2. Shaima Wahab says

      August 27, 2024 at 4:54 am

      No, that's only necessary for the process. After that, just leave it in the fridge in an airtight container, and it'll last for months. I'm not even kidding, I had a little leftover that I transferred to a small plastic container, so I could use the jar for the new batch, and I forgot about the leftovers for months. When I realized they were still sitting there like six months later, I tasted it and it was still perfectly fine.

      Reply
    3. Jennifer says

      June 09, 2024 at 3:28 pm

      5 stars
      I'm trying to eat more fermented foods and learn to like them better. Last month I found this recipe and fermented them the full 7 days, these are now my favorite fermented food! My kids Even eat them on everything!

      Reply
    4. Mike says

      April 30, 2024 at 1:11 am

      Hello, does it have to be distilled water? Is it better for the fermenting process?

      Thanks
      Mike

      Reply
      • Christy Faber says

        May 01, 2024 at 9:01 pm

        Some people have found tap water to negatively effect the fermentation process so I've always found it safest to just use distilled water so I don't waste any ingredients. 🙂

        Reply
        • Bob says

          June 21, 2024 at 10:31 pm

          I always boil the water in advance - it boils off the Chlorine added to our tap water.
          Next, I let it boil for a little bit to be sure. Then I let it cool to room temp.
          Last, I use it in my Ferments.

          Reply
    5. Anna Pedret-Dunn says

      April 15, 2024 at 12:44 pm

      Followed the recipe which was very easy, except I left my jar on the kitchen counter in day light (but not in direct sun light) for the first 24h, but should it be stored somewhere dark, ideally? I have put it in the cupboard now though it might be a little late.

      Looking forward to trying result in any case.

      Reply
    6. Beck says

      March 01, 2024 at 2:40 am

      Is there a way to make this shelf-stable vs fridge stored?

      Reply
      • Christy Faber says

        March 03, 2024 at 2:11 pm

        If kept on the counter the onions will continue to ferment so they will get tangier and tangier and even a little effervescent. Storing them in the fridge will halt the fermentation and keep them stable for months. Hope this helps!

        Reply
    7. Chris says

      February 23, 2024 at 9:32 am

      Hi, I was wondering if once placed in the fridge after the initial fermentation at room temperature, is it still critical to use weights to maintain an anaerobic environment in the fridge? Or once in the fridge is it okay not to use weights and vegetables aren't fully submerged anymore without as much of an anaerobic environment? Thank you!

      Reply
    8. Hayley Dhanecha says

      May 13, 2023 at 4:25 am

      5 stars
      I have many onions in my pantry that are almost impossible to finish in my cooking, will ferment some of them using your recipe. thnaks for all the tips!

      Reply
    9. Jenny says

      May 08, 2023 at 5:04 am

      5 stars
      This is very informative; I enjoyed reading your post. We have tried pickled onions but never fermented onions. I am curious to try this, it looks doable and I am curious about their taste. Thank you.

      Reply
    10. silvia says

      May 08, 2023 at 3:55 am

      I usually pickled my onions, but I've been researching about fermenting them. You have given me a lot of great tips and something to think about. I'm just waiting to get my onions from my home garden and I'll get to work!

      Reply
    11. Dee says

      May 07, 2023 at 6:45 pm

      5 stars
      I think I'll start pickling my onions like this. I normally just throw them in the fridge submerged in vinegar without any rhyme or reason. Thanks for the great tips.

      Reply
    12. Carrie Robinson says

      May 07, 2023 at 5:20 pm

      5 stars
      I have never heard of this process before, but now I am totally intrigued! 🙂 The healthy benefits sound absolutely amazing.

      Reply
    13. Veronika says

      May 07, 2023 at 8:57 am

      5 stars
      I love making my own fermented food! Never tried it with onions and cannot wait to make this recipe this weekend 😉

      Reply
    14. Leslie says

      May 06, 2023 at 10:36 am

      5 stars
      You have had the exact concerns I have had when contemplating whether or not to ferment vegetables on my own. I appreciate this post more than you know!

      Reply
    15. Sean says

      May 02, 2023 at 6:48 pm

      5 stars
      Such a great way to get your probiotics and I love sauerkraut. How long can I keep them. Are they still good after about a month?

      Reply
    16. Bernice says

      May 02, 2023 at 11:43 am

      I make sauerkraut quite often and have tried fermenting pickles. The kids didn't like the difference in flavour from their regular dills. I never even thought about fermenting onions! I'm very curious and I think they would be great in so many dishes.

      Reply
    17. Gloria says

      May 01, 2023 at 12:48 pm

      5 stars
      We love sauerkraut, so I find this recipe very interesting. I always have pickled onions in the fridge. This will be a nice alternative for sure.

      Reply
    5 from 10 votes (1 rating without comment)

    Leave a Reply Cancel reply

    Your email address will not be published. Required fields are marked *

    Recipe Rating




    Primary Sidebar

    Welcome,

    I’m Christy

    a happy wife and mother to three boys, a nutritionist, a food lover and a Canadian. Creating and experimenting in the kitchen is my idea of an afternoon well spent. To me, a clean kitchen is an empty canvas of possibility and that means my kitchen never stays clean for long. My dream is that one or more of the recipes I share here will inspire you, perhaps even becoming a cherished family favourite.

    READ MORE >

    Spring Desserts

    • Strawberry Rhubarb Mousse
    • Lemon Panna Cotta
    • Cheesecake Lime Tart
    • 5 Pieces of Blueberry Cottage Cheese bark on a ceramic plate on a staged counter top with frozen blueberries and oats around.
      Blueberry Frozen Cottage Cheese Bark
    • Lemon Lime Green Grape Sorbet
    • Honey Lemon Tart

    Spring Salads and Appetizers

    • Carrot Ribbon Salad with Arugula
    • Mediterranean Orzo Salad with Grapes
    • Quinoa Salad with Roasted Veggies
    • Pear and Blue Cheese Endive Boats Appetizer
    • Halloumi skewers featuring melon balls on a serving plate beside a glass of white wine.
      Melon and Prosciutto Skewers with Halloumi
    • Balsamic Green Beans with Crispy Bread Crumbs

    Most Popular

    • Gluten-Free Buckwheat Flour Brownies
    • Five coconut flour oatmeal cookies stacked on top of each other on a cooling rack with others around.
      Healthy Coconut Flour Oatmeal Cookies
    • Strawberry cottage cheese smoothie pouring into a glass out of a blender cup on a staged tabletop.
      Strawberry Cottage Cheese Smoothie
    • Date Sweetened Chocolate Chip Cookies
    • Custard Oats with Mixed Berry Compote
    • Green, dessert bowl full of Cottage Cheese Lemon Mousse on a wooden board with a handle spooning a scoop out.
      Cottage Cheese Lemon Mousse

    As featured in

    Naturally Sweetened

    • Healthy Chocolate Pudding
    • stack of fudgy oat flour brownies on a white board.
      Oat Flour Brownies
    • Peanut Butter Swirl Black Bean Brownies
    • Homemade Strawberry Mint Ice Cream
    • a bowl of date paste topped with flaky salt on a countertop with a few medjool dates beside the bowl.
      Date Paste
    • Super Nourishing Custard Drink

    Follow For More Recipes

    • Instagram
    • Facebook
    • Pinterest
    • Home
    • Recipe Index
    • Sides and Appetizers
    • About Me
    • eBooks
    • Subscribe

    Copyright © 2025 Life Around The Table | Accessibility | Privacy policy


    Rate This Recipe

    Your vote:




    A rating is required
    A name is required
    An email is required

    Recipe Ratings without Comment

    Something went wrong. Please try again.