Hunan chicken has a hot and spicy flavour because it is marinated and stir-fried with chili peppers, shallots and garlic. This particular cooking style originates in, and takes its name from, the Hunan region of western China.
Hunan cooking is similar to Szechuan-style cooking, another hot and spicy Chinese cooking method. The main difference lies in the use of whole chili peppers and seeds rather than chili bean paste. This makes the dishes even hotter. A distinction is also made between the "dry hot" of Hunan cooking and the "numbing hot" of Szechuan.
Spicy foods, often flavored with locally grown chilis, are popular in hot, humid climates because the intense warmth has a cooling effect on the body. The hotness of the dish is controlled by the type and amount of chili pepper used.