What are chili peppers? When do you use chili pepper? What are the uses of chili peppers? Chili peppers are important cooking ingredients used in most Asian recipes for cooking spicy Asian cuisines and the most popular type of chili pepper used to cook Asian food are red hot chili peppers. Chili pepper which is also called chilli pepper, chilli, chillie, chili, or chile, or chili hot pepper, is the fruit of the plants from the genus capsicum.