Mustard means mustard. The Book of Rites says, "Spring onions, autumn mustard." It means that in cook the meat, onions are added in spring and mustard is added in autumn. There are six kinds of mustard in China: leaf mustard (such as Xuelihong), stem mustard (such as mustard tuber), stem mustard, bud mustard, mustard seed mustard and root mustard. Generally speaking, mustard refers to leaf mustard or stem mustard. Pickling mustard into pickles has a special flavor and can be used as a dish to adjust the taste. Mustard is rich in vitamins, iron and potassium, which can help treat some vitamin deficiencies and prevent cancer. But the main function of mustard is appetizing. Li Shizhen said in Compendium of Materia Medica: "Mustard is appetizing." Boiling mustard and ginger together has a good therapeutic effect on patients with weak digestive ability. Mustard seeds can be ground into fine powder to make spices, that is, mustard, which tastes very spicy. There is an old saying: "Looking at plums to produce saliva, eating mustard leaves to shed tears."