The term “mustard” is used to describe several plants in the Brassica and Sinapis genera which are used as sources of food. There are a number of different types of mustard which are cultivated for different products, including greens and leaves. The incredible diversity and flexibility of mustard plants can cause them to pop up in a wide variety of places, from traditional American Southern cuisine to fiery Indian curries.
Three different types of mustard are used as a source of seeds, which can be ground up and used as a condiment, added to pickling mixtures, or included whole in an assortment of marinades, sauces, and curries. S. albis produces “white” mustard seeds, which are actually yellow; these seeds provide the most mild flavor, and they are used to make classic mild and table mustard. The electric yellow condiment used on hot dogs in the United States is derived from white mustard seeds.
B. juncea produces brown seeds which are hotter than white mustard seeds, while B. nigra produces black seeds with a very strong and distinctive flavor. Black mustard is often used in Indian and Southeast Asian cooking, where it is incredibly popular; you may have encountered whole mustard seeds in marinades and curries if you eat a lot of Southeast Asian food. Both black and brown types of mustard can also be ground into condiment form.
As a condiment, mustard is incredibly diverse. Mustard can be ground into a smooth puree or mixed with whole seeds for more texture. It can also be blended with things like horseradish for spicy mustard, which can be quite fiery, or sugar, for sweet mustard. Some cultures have a tradition of making mustard with beer or wine, creating a very distinctive, complex flavor which complements a range of foods. Mustards can also be blended with oranges, cranberries, and other fruits or herbs; these types of mustard are often treated as gourmet items. You may have noticed a wide assortment of types of mustard on sale at your local market, illustrating the dizzying array of things which can be blended with mustard.
The spicy yellow mustard used in Chinese food and some British cooking is a form of mustard which has been ground and then dehydrated, concentrating the spicy flavor. You may have noted that this mustard can be incredibly hot, especially if it has been allowed to sit so that the flavor develops. Mustard greens come from the brown mustard plant, typically, and they have a spicy flavor which complements soups and stir fries or does well on its own as a side dish.