Lacto-fermented Onions

Mixed onions

By Cat, Oct 2017 (Photo, right, from Wikimedia Commons; and below from Pickl-it (4))

A friend just gave me a bunch of onions and shallots from her garden, more than I can eat before they go bad, so I’ve decided to ferment (pickle) them. I know I need to eat a forkful of fermented foods each day, and fermented onions are delicious.

Pickle-it Jar

Fermenting at home is really easy – the hardest part is peeling and slicing. All you need are the food to be fermented, distilled or filtered water, non-iodized salt, optional herbs/spices, and a mason jar. Or better yet, use a Pickl-it jar with anaerobic air-lock.

See also: 1. Culturing, Curing, Fermenting Menu; 2. Pickling and Lacto-Fermentation (About); 3. Lacto-Fermented Garlic

Lacto-Fermented (Pickled) Onions

I’ve adapted this recipe from several sources: Juicing for Health on lacto-fermentation and includes a recipe for pickled onions (1); Cultures for Health: Lacto-Fermented Purple Onions (2); Padaek’s Lao-Australian Food Blog (3); Almost Bananas (4), and Delicious Obsessions (5). The method for all of these is basically same; what differs is the kind of salt used, and the herbs, spices and other veggies added for their flavors.

You can use any variety of onion and/or shallots; you can use only one variety, or you can mix them up. Most recipes add garlic. For my test recipe, I plan to use yellow onion and shallot to make a pint of pickled product. I may also add a bit of red or purple onion for the color (and the benefits of the anthocyanins and polyphenols that provide the purple color).

I use a wide-mouth Mason jar with a lid as the fermentation vessel; another great option is to use a jar with an anaerobic air lock, such as Pickl-it (or use a kit to fit a Mason jar with an anaerobic air lock).

For the brine, you either coax the moisture out of the onions with the salt, or mix distilled or filtered water with the right amount of salt to form a 2% brine. For the salt, you can use kosher salt, sea salt, or non-iodized table salt; these differ in the size of the salt granules, so it is best to weigh them in grams rather than using teaspoons/tablespoons. Pick-it has an easy-to-use calculator (6) that determines grams of salt for amount of water needed to cover the veggies. DO NOT USE IODIZED SALT for the brine.

To determine amount of water and salt needed for the brine:  You want a 2% brine, which is 19 grams of salt per 1 liter/quart of filtered water; I describe 2 methods to accomplish this in the recipe below.

Additional ingredients: Flavorings commonly used with onions are: anise, star anise, allspice, coriander and mustard seeds; black peppercorns; chile peppers; minced garlic; and bay leaves.

Raw or minimally-processed dehydrated cane sugar can also be added to the brine; see Padaek’s recipe (3) for details.

Ingredients & Equipment

  • onions
  • non-iodized salt
  • distilled or filtered water
  • desired herbs/spices to flavor (I used coriander seeds and black peppercorns)
  • sugar (optional)
  • Equipment:
  • bowl
  • wooden spoon or meat pounder (brine method #1)
  • saucepan (brine method #2)
  • Mason jar(s) with regular or airlock lid
  • towel


  1. Prep the onions: cut off the root and remains of the stem; then remove peel. Slice or leave whole.
  2. Prep the garlic clove: remove peel, then mince.
  3. Determine amount of brine needed, and amount of water and salt to make the brine; or amount of salt to mix with the moisture in the onions. See “Determine amount of salt and water for brine,” above, for details.
  4. Determine flavor ingredients. I highly recommend using at least black peppercorns and minced garlic (1 clove or more per quart of fermented product).
  5. Sterilize your jars and lids.
  6. At this point there are two ways to put it all together:
  7. Brine Method #1: Weigh prepped onion and garlic in grams; multiply that weight by 2% (0.02) to determine amount of salt in grams. For example, if you have 500 g of onion/garlic, multiply by 0.02 to get 10 grams salt.
  8. Place onion/garlic in bowl, sprinkle predetermined amount of salt over and press with wooden spoon or meat pounder to release the moisture. Cover bowl and let rest for 10 – 20 minutes on the counter (2), or 3 hours in the fridge (3) to draw out more moisture.
  9. Place herb/spice flavorings in bottom of sterilized jar. Cover with onion/garlic mix and press down. Be sure to leave at least 1″ of headspace in the jar.
  10. If the moisture from the onion/garlic mix is not enough to cover the mix, add distilled/filtered water to cover, leaving 1″ of headspace.
  11. Brine Method #2: Place herb/spice flavorings in bottom of sterilized mason jar. Cover with prepped onion/garlic mix; press down. Pour distilled/filtered water over them to cover, keeping track of the number of cups added (or, after covering with water, place a sieve over a quart-sized Pyrex measuring cup; dump contents of jar into sieve and allow the water to drip into the measuring cup. Read the amount of water in cups)
  12. Determine amount of salt: The easiest way is to use the Pickl-it calculator (6): select 2% brine, enter amount of cups or quarts (for example, 1.5 cups) and it automatically displays the number of grams of salt, 7 grams in this example. Or long-hand: you want 19 grams salt per liter/quart of water; so convert the cups to fractions of a quart (for example, 1 ½ cups is ⅜ of a quart so multiple 19 times ⅜ to get 7 grams).
  13. Warm the determined amount of water in a saucepan; stir in the determined amount of salt until dissolved. Let cool, then pour over onion/garlic mix.
  14. Ferment: Cover jar with a regular lid or an airlock fermentation lid.
  15. Cover all with a towel to keep out the light, and set on counter to ferment 1 – 2 weeks, burping the jar each day, until active bubbling stops. Be sure to burp the jar every day. If you don’t use an airlock lid, you can taste the onions for flavor.
  16. Store: When ready, transfer to cold storage (a root cellar or refrigerator).
  17. Next batch: Save some of the brine from each batch, to inoculate successive batches; brine from fermented garlic or onion is great to inoculate other vegetable brines as well.


  1. Juicing for Health recipe & article:
  2. Cultures for Health recipe:
  3. Padaek recipe:
  4. Almost Bananas recipe:
  5. Delicious Obsessions recipe:
  6. Pickl-it jar image:; brine calculator:

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