Mustard sauce is a condiment made primarily from ground mustard seeds, vinegar, and water. It can vary in flavor from mild to spicy, depending on the type of mustard seeds used and additional ingredients. Common varieties include yellow mustard, which is often used on hot dogs, and Dijon mustard, known for its smooth texture and tangy taste. This sauce is popular in many cuisines around the world and can be used in salad dressings, marinades, and sandwiches. It adds a zesty kick to dishes and can also be combined with other ingredients, such as honey or herbs, to create unique flavors.