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–+ servings
a photo of a jar of Spicy Fermented Mustard 1

Spicy Fermented Mustard

Fermenting mustard enhances its flavour complexity, improves digestibility, and adds natural probiotics that support gut health and immunity. This mustard is super easy to make and has a depth of flavour you won’t find in store-bought varieties!

Takes 6 days 20 minutes

Serves 20

Ingredients
 

  • 200 g yellow mustard seeds
  • 50 g brown mustard seeds
  • 1 fresh red chili or ½ tsp dried chili flakes, adjust to taste (approx. 15-20g)
  • ¼ garlic bulb approx. 15g
  • ½ small lime approx. 25g
  • 500 ml filtered water for the brine
  • 2 tsp 10g sea salt (non-iodized)
  • 1 tbsp maple syrup or honey optional, for balance
  • 50 ml reserved fermented brine for adjusting consistency after blending
  • 4 tbsp apple cider vinegar optional, for extra tang after fermentation

Instructions
 

Prepare the Brine & Ferment the Mustard Seeds

  • Dissolve 10g sea salt into 500ml filtered water to create a 2% brine solution.
  • Place the yellow and brown mustard seeds in a sterilized jar.
  • Add the chopped chili, ½ lime and minced garlic (if using) on top of the mustard seeds.
  • Pour the brine over the mustard seeds, chillies, lime and garlic, ensuring they are all fully submerged.
  • Weigh the seeds down with a clean glass to keep them submerged.
  • Cover loosely with a lid or cloth and let it  ferment at room temperature (18-22°C) for 5-7 days.
  • Check daily for bubbles and a tangy aroma.

Blend & Adjust

  • Drain the fermented mustard seeds, reserving the brine.
  • Blend the seeds with 2 tbsp of reserved brine and add more until you reach your desired texture. Blend for longer if you want a smooth homogenous mustard or for less time if you want a chunky wholegrain mustard.
  • Stir in maple syrup and apple cider vinegar for balance and ensure to season to taste adding more salt or vinegar till you reach your desired taste.

Store & Age for Flavor Development

  • Transfer the mustard to a clean, sterilized jar.
  • Store in the fridge, where it will continue to develop flavor over time.
  • For best taste, let it mature for 1-2 weeks before using.

Notes

Why Ferment Mustard?

✅ Enhanced Flavor Complexity

  • Fermentation mellows bitterness and creates a deeper, umami-rich mustard with tangy, slightly funky notes.
  • Natural lactic acid bacteria (LAB) create a subtle sourness that complements the mustard’s heat.

✅ Improved Digestibility

  • Soaking and fermenting mustard seeds can reduce antinutrients, making the nutrients more bioavailable.
  • It can also reduce mustard’s naturally strong heat, making it smoother.

✅ Probiotic Benefits

  • If fermented with lactic acid bacteria (like those from sauerkraut or whey), it can contain gut-friendly probiotics.

✅ Natural Preservation

  • Fermentation naturally acidifies the mustard, helping it last longer without relying solely on vinegar.
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