For mild mustard, combine the water and vinegar and bring to a boil, then mix in the dry ingredients. Use cold liquids for hotter mustard. For variations, try substituting a dry white wine or lemon juice in place of the water.
Mustard can be any type: mild, regular or oriental. Add whole or crushed mustard seeds after completing the basic recipe. They adsorb a lot of liquid. If extra liquid is needed, consider using vinegar first.
Use this recipe as a base to create flavored mustards to your taste.