For best flavor, let the sauce rest longer—up to a few hours or overnight—in the refrigerator so the mustard and spices fully bloom, and stir before serving in case any separation occurs; you can thin the sauce with a teaspoon or two of water or milk if it becomes too thick, or make it spicier by adding a pinch of cayenne or extra Dijon, and it will keep well in an airtight container in the refrigerator for about 5–7 days, making it easy to prepare ahead for parties, game days, or snacks.