From-scratch mustard is surprisingly simple to make and will last about 6 weeks stored in the refrigerator. For a smoother version, grind the mustard seeds longer. This recipe is for a more rustic version, not to be confused with the spicier Dijon.
Nicole Spiridakis for NPR
Makes 1 cup, easily doubled
6 tablespoons mustard seeds
1/2 cup mustard powder
2 teaspoons salt
1 tablespoon honey
3 tablespoons apple cider vinegar
1/2 cup water
In a spice grinder or with a mortar and pestle, grind the mustard seeds for a few seconds. (You'll leave them mostly whole.)
Put the seeds into a bowl and add the mustard powder, salt, honey, apple cider vinegar and water. Stir well. Pour into a glass jar and store in the refrigerator for at least 24 hours to let the flavors blend before using.