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Fermented Red Onion Recipe

Fermenting red onions is easy, quick, and makes the most perfect, thinly sliced condiment for salads, sandwiches, soups, etc. It takes a little longer than quick pickled onions, but the short wait is SOOOO worth it!
Course: Ferment
Keyword: Onions
Author: nourishingtime.com


  • Mandoline or knife
  • 1 L jar
  • Airlock lid (I use Pickl-It) recommended
  • mixing bowl
  • Kitchen scale


  • 2 lb red onions approximately 2 large onions
  • 8 g salt
  • 1/4 small beet (optional, for color)


  • Peel the red onions and remove the ends.
  • Put mixing bowl on kitchen scale and zero it out.
  • Slice red onions thinly and move to the mixing bowl. Using a mandoline will help create uniformly thin slices.
  • Note the weight of the sliced red onions in mixing bowl. It should be around 1.5lbs. If you have more than this, remove the extra. You can use the rest in dinner, a salad or refrigerate/freeze for future use.
  • At this point you can slice the beets and put at the bottom of your fermenting jar OR shred and add to the onions.
  • Add salt (approximately 8g or 1.5 tsp) and mix well.
  • Move red onions to your fermenting jar, pressing down gently as you go along. Make sure your jar is clean and you don't fill past the shoulder. Onions tend to create plenty of juice so making the cut off the shoulder or a little below is pretty wise!
  • Let ferment for one week at room temperature, and one week in the fridge. This is a ferment you will want to put on something to catch excess liquid just in case it leaks!
  • Enjoy!!!