- 2/3 cup water
- 1/2 cup mustard seeds
- 3 tablespoons dry mustard powder
- 3/4 cup white wine vinegar
- 2 teaspoons kosher salt
- Blend water, mustard seeds, and mustard powder in a blender until seeds are coarsely ground; transfer to a non-reactive bowl, cover with plastic wrap, and let rest at room temperature until thickened, 4 hours to overnight.
- Stir vinegar and salt into the mustard seed mixture.