Mustard is a fascinating condiment, brightening our plate and palate. Strictly speaking, mustard is not really a product of fermentation but we use a fermented liquid (beer in this case, but it could be kombucha or kraut brine as well) to hydrate the seeds. Mustard seeds are exceedingly antimicrobial, explaining the longevity of the final product. Adding a hot or cold liquid to the seeds has an impact on the heat level. A warm infusion mellows out the bitterness of the mustard seeds while a cold soak favors a spicier mustard. The two mustard preparations below are made with two different Belgian beers. For the first one, the mustard seeds are soaked in a warm reduction of beer (triple naturelle) and spices and blitzed afterwards. For the second one, the seeds are soaked in the cold Stout and spiced up just before blitzing, leaving a distinct roasted malt taste.

1. Beer & honey mustard
Ingredients:
4 Tbsp yellow mustard seeds
1 Tbsp mustard powder
1 small shallot, finely chopped
1 garlic clove, minced
125 ml beer – Curieuse neus (Brasserie En Stoemelings)
75 ml apple vinegar
2 Tbsp honey
1 tsp turmeric
1 tsp grated nutmeg
1 tsp salt

Instructions:
Put the beer, vinegar, honey, salt, onion, garlic, nutmeg and turmeric into a small casserole and bring to a boil for about 15 minutes until reduced to half. Pour the liquid over the mustard seeds in a glass jar. The soaking seeds will start to swell so use a jar with some extra space. Close the jar and let everything infuse for at least two weeks or longer if you can, at room temperature, stirring the seeds every other day with a clean spoon. Blitz to a coarse texture and transfer to a clean jar. Keep in the fridge for at least a month before serving.

Note: I added a good splash of homemade tarragon vinegar before blitzing, to add some extra depth and a sour hint.

2. Stout and maple mustard (inspired by great British chefs)
Ingredients:
60 gr yellow mustard seeds
150 ml beer Ardenne Stout (brasserie Minne)
1/2 tsp salt
50 ml malt or black vinegar
1/4 tsp Marmite
1 Tbsp maple syrup

Instructions:
Put the beer and the mustard seeds in a glass jar, cover with a lid and leave everything to infuse for at least two weeks at room temperature, stirring the seeds every other day with a clean spoon. Transfer the mixture to a blender and add the other ingredients, blitz to the texture you like. Taste and adjust the seasoning and transfer to a clean jar. Keep in the fridge for up to a month before serving.