Mustard sauce is a condiment made primarily from ground mustard seeds, vinegar, and water. It can vary in flavor and heat, depending on the type of mustard seeds used and additional ingredients. Common varieties include yellow mustard, which is mild and tangy, and Dijon mustard, known for its smooth texture and sharper taste. This sauce is often used to enhance the flavor of foods like sandwiches, hot dogs, and burgers. It can also serve as a base for salad dressings or marinades. Mustard sauce is popular in many cuisines around the world, adding a zesty kick to various dishes.