Mustard seed, one of the oldest of spices, adds warmth and heat to your dishes. It"s spicy, peppery flavor goes well with other pungent spices like garlic and chilies. The best way to fully release the flavor, then, is to mix the seed with warm water for about ten minutes before adding it to a recipe. To stop the development of the flavor, on the other hand, add an acidic liquid, like lemon juice, vinegar, or wine, to your recipe. To make your own condiment, mix ground mustard with vinegar and water (to suit your taste).