The mustard used in cooking is a condiment made from the seeds of the mustard plant, ground and mixed with vinegar or wine, salt and spices. The most famous is Dijon, smooth and sharp; wholegrain mustard keeps the seeds whole.
A teaspoon of mustard acts as an emulsifier in vinaigrettes and vegan mayonnaise, helping oil and liquids bind. It adds character to yogurt sauces, potato salads and dressings for raw vegetables.