Douchi or tochi is a type of fermented and salted black soybean most popular in the cuisine of China, where they are most widely used for making black bean sauce dishes.
Douchi is made by fermenting and salting black soybeans. The black type soybean is most commonly used and the process turns the beans soft, and mostly semi-dry (if the beans are allowed to dry). Regular soybeans (white soybeans) are also used, but this does not produce "salted black beans"; instead, these beans become brown. The smell is sharp, pungent, and spicy; the taste is salty, somewhat bitter and sweet. The product made with white soybeans is called mianchi.
Douchi, "Chinese salted black beans", and "black soybeans" are not the same as the black turtle bean, a variety of common bean that is commonly used in the cuisines of Central America, South America, and the Caribbean.