Hot mustard refers to a type of mustard condiment that is known for its spicy and pungent flavor. It is made from mustard seeds that are ground into a paste and mixed with other ingredients, typically vinegar, water, and seasonings. The heat in hot mustard comes from compounds found naturally in mustard seeds called isothiocyanates.

Hot mustard is commonly used as a condiment for a variety of dishes, including sandwiches, hot dogs, sausages, and as a dipping sauce for pretzels or fried foods. It can add a spicy kick to your favorite dishes and is a staple condiment in many cuisines around the world.