Lacto-Fermented Purple Onion Relish


It may not seem like it as the days get colder, but now is a great time to culture all sorts of different vegetables. The cooler temperatures in your home are more conducive to longer-fermented, tastier cultured vegetables than the warmer summer temperatures.

So why not try your hand at all sorts of different flavors and textures when the time is right? Find recipes for all sorts of different cultured vegetables, including this purple onion relish. This is a great way to preserve notoriously hard-to-keep purple onions.

Use this recipe to add great flavor and color to sandwiches, burgers, and salads.

Lacto-Fermented Purple Onion Relish


  • 3 medium-sized purple onions, diced coarsely
  • 2 tablespoons whole black peppercorns (optional)
  • 1 to 2 teaspoons sea salt
  • Filtered water
  • Whey or brine from a previous ferment


  1. Place the purple onions and the peppercorns into a medium-size non-reactive bowl. Sprinkle with 1 to 2 teaspoons of salt, then stir and pound lightly with a wooden spoon. Cover the bowl with a towel and allow the onions to sit undisturbed for 10 to 15 minutes.
  2. Scoop the salted onion mixture into two clean pint jars, leaving about an inch of space from the top of the jar. Press the relish down with your wooden spoon to compact it and cause the juices to rise.
  3. Fill the remaining space in the jars with filtered water, leaving 1 inch of headspace. You can add a teaspoon of starter at this point; fresh whey or a brine from a previous ferment will do well. Cover the jars with lids (you can use an airlock or a regular lid) and allow them to sit at room temperature away from drafts and direct sunlight for 4 to 5 days. You may have to burp the jars and press the relish down into the liquid once in a while, so keep an eye on the jars while they are fermenting to determine what they may need.
  4. Once the relish has become bubbly and fragrant, place the jars in cold storage until you are ready to use them.

This relish will keep sealed in the refrigerator for 6 to 7 weeks.


Shannon is a mama to four small children, homesteader, freelance writer, and picture-taker. She lives with her husband on their off-grid homestead where they make and eat kefir, kombucha, sourdough, and fermented vegetables.

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