My favorite way to use it is as the basis for homemade vinaigrette dressing, the vital topper for my daily, unprocessed, salad at lunch. Mustard you make yourself will be a bit spicier than commercial varieties.
¾cupwhey or pickle brine
½cupmustard seedsbrown or yellow—the brown are hotter and will make a spicier mustard
1tablespoonfinely chopped shallots or ½ tablespoon minced garlic
saltif using whey
Combine the whey, mustard seeds, and shallots or garlic in a bowl and allow to soak at room temperature overnight.
In a blender or food processor, mix the soaked seeds with the maple syrup, and blend until you get a texture you like, which can take several minutes. Taste for salt and correct the seasoning. Store in a sealed jar in the fridge, where it will keep for many months.