Fermented Onions: Lacto-fermented with probiotics

Fermented onions are one of the most delicious condiments. Unlike pickled onions, these lacto-fermented ones use brine for optimal health benefits.

Onions are a kitchen staple in our kitchen, I use them in almost every recipe. They add a unique flavor to meats, sauces, soups, and even syrups or cough teas. I love onions: fried, baked, pickled, fresh and fermented. However, my daughter is sensitive to fresh raw onions; she finds them too strong and always picks them out of sandwiches or salads. Fermented onions are the perfect alternative for her, easier to digest. Rich in enzymes and probiotics, fermented onions are less pungent and create a fresh condiment perfect for salads or stir-fries. 

I love keeping fermented onions or cauliflower in my fridge to add a nutritional boost to my lunch bowls.

Moreover, fermenting onions at home is incredibly simple, one of the easiest ferments to try. With just a few basic ingredients likely already in your kitchen, you can create a condiment that enhances any sandwich or burger.

What are lacto fermented onions?

Unlike pickled vegetables, lacto fermented onions use a traditional, natural fermentation method that requires no added ingredients like vinegar, whey or starter cultures. All you need are salt, water, and the onions themselves.

Similarly, you can ferment fruits like apples, bananas, sauerkraut or kefir.

However, fermented onions have a unique probiotic profile, different from other fermented foods, which can surprise many people! The fermentation process creates beneficial bacteria specific to onions, adding to their health benefits and distinctive flavor.

Lacto-fermentation process

Lacto-fermenting onions is an easy way to preserve them and boost their flavor and nutrition. To start, onions are placed in a saltwater brine, which keeps out harmful bacteria and allows good bacteria (lactobacillus) to grow.

These beneficial lactic acid bacteria eat the sugars in the onions and produce lactic acid. This natural acid helps preserve the onion and adds a deliciously tangy taste.

Depending on temperature and taste preference, the process takes about 1-2 weeks. Once fermented, you can store the onions in the fridge for months and use them every time you need to add a probiotic kick to meals.

Ingredients to make lacto-fermented onions

• For onions, you can use any onion varieties from red onions, white, yellow, to even cocktail onions. Peel them first. Small onions can be used whole or you can slice them. If you have an abundance of small or cocktail onions, this creamed onions recipe is a keeper.
• sea salt or table salt
• filtered water
• cayenne pepper or curry powder
• chili pepper
• caraway seeds or any other herbs and spices like dill 

See the recipe card for quantities.

Tools for the fermentation process

• A fermentation vessel (such as a ceramic crock or a mason jar). T
• Fermentation weight (such as a plate or a smaller jar filled with water)
• A clean cloth or coffee filter to cover the vessel
• use pH meter to monitor the acidity of the ferment; it will give you a good idea.

Fermented Onions Recipe

First step – Prepare the Onion

Prepare the onions and start by cutting off the woody ends and peeling them. Slice them into thin rings or wedges. You can also leave small onions whole.

Second step: Make the brine

In a large mixing bowl, dissolve 1 tablespoon of sea salt in 2 cups of filtered water. Stir until the salt is completely dissolved. Pour the brine over the onion and use your hands to massage and mix everything. 

Third step: Transfer the ingredients to a fermentation crock or a jar.

Once the the sliced onions (or whole onions) is well coated, transfer it to a clean, wide-mouth gallon jar or a fermentation crock. Ensure that you covered all the veggies with brine and that you removed all air bubbles. Add chili pepper and press it down firmly, and insert a disc to help all the contents stay completely submerged in the brine. You can also use glass weights that are easy to wash. 

Fourth step: Ferment

Seal the jar with an airlock system or screw a lid on loosely, allowing CO2 to escape, or use an airlock.

Cover the jar with a clean cloth or coffee filter, and secure it with a rubber band or string. Ferment at room temperature, away from direct sun light, it takes 5-7 days. Check the onions daily to make sure they stay fully submerged in the brine. If you are using a sterilied jar, don’t forget to burp the jar, every day,  opening it to release any built-up gases. Taste after 3 days and continue fermenting until you reach the desired level of sourness.

Once fermented, seal the jar with a tight lid and refrigerate. The onions will continue to ferment slowly in the fridge and can last for several months.

Ways to use and eat fermented food

Fermented onions are delicious and versatile, adding a tangy, probiotic boost and probiotic bacteria that benefit gut health.

• Enjoy fermented onions straight from the jar as a quick snack or pair them with cheese for a light snack
• Use fermented vegetables to top sandwiches, burgers or wraps. I also make tacos, burritos or quesadillas with fermented onions.
• Toss fermented onions into leafy green salads or grain-based salads or to coleslaw for extra flavor and crunch.
• if you like grain bowls, top rice, quinoa, or couscous bowls with fermented onions to enhance the flavor.
• Mix into lentil soups or bean salads for an added layer of taste.
• Add fermented onions as a tangy, flavorful element to a charcuterie board alongside cheeses, meats, and crackers.
• Blend them into sauces, aiolis, or dressings for extra flavor.
• Lastly, serve them as a side dish with roasted meats, fish, or roasted vegetables.

How to store the fermented onions?

Store the onion in the refrigerator to slow down the fermentation process and to prolong the shelf life.