Recipe: Fermented Mustard

We love having a fridge packed with fermented condiments, they are easy to make, last quite some time and elevate even the slapdash meals and takeout to something special. We always have homemade fermented ketchup, several varieties of fermented hot sauce, and this fermented mustard on hand.

Making your own mustard is great because you control the heat level, acidity and consistency so that you’re making the perfect mustard for you. And mustard seeds are kind of magic. At the absolutely simplest you could just add water to them and it would become mustard (and fun fact: the colder the water, the spicier the mustard will be). Adding in an acid (in the form of vinegar or a fermented brine) will add a lot of flavor and the acidity helps preserve the mustard heat.

We love using leftover hot sauce brine for a spicier mustard, but you can use kraut brine or whey if you’re looking for something milder. The fermentation is quick, just 2-3 days on the counter and then it’s ready to blend. Whether you want whole grain, half cracked, or silky smooth is totally up to you.

Recipe: Fermented Mustard


  • 2 cups yellow mustard seeds

  • 2 cups brown mustard seeds

  • 2 tablespoons mustard powder

  • 1 - 2 cups hot sauce brine (for a milder mustard use kraut brine or whey)

  • 2 - 3 cups water

  • 1/4 cup maple syrup

  • 1 teaspoons salt

  • 1/2 - 1 cup vinegar


  1. In a 1/2 gallon glass fermenter (Check our out Fermented Veg Kit), combine yellow mustard seeds, brown mustard seeds, and mustard powder.

  2. In another mixing bowl, combine hot sauce brine, water, and maple syrup. Add salt. Whisk to dissolve. Note: Colder liquid (from the refrigerator) can result in a hotter mustard.

  3. Add liquid ingredients to glass fermenter, combining with dry ingredients.

  4. Top fermenter with lid and airlock (See how to assemble an airlock). Let fermenter sit at room temperature for 2-3 days.

  5. After fermentation, add vinegar to fermenter and stir to combine.

  6. Blend mustard mixture in batches using a food processor or blender. Blend to desired graininess. Add salt and additional vinegar to taste.

  7. Transfer to jars or reused mustard containers. Store in the fridge. Fermented mustard will keep refrigerated for at least 2 months. 

Fermenting Picks:

Kraut Kit
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Fermented Vegetable Kit
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