Douchi is a type of fermented and salted soybean. In English it is known simply as "black bean", and is also called fermented black soybeans, Chinese fermented black beans, salted black beans, salty black beans, or just "black beans". They are a flavoring most popular in the cuisine of China, where they are most widely used for making black bean sauce.
Douchi is made by fermenting and salting soybeans. The black type soybean is most commonly used and the process turns the beans soft, and mostly dry. Regular soybeans are also used, but this doesn't produce "salted black beans", instead these beans become brown. The flavor is sharp, pungent, and spicy in smell, with a taste that is salty and somewhat bitter and sweet.
The process and product are similar to ogiri and iru, both being African fermented bean products.
Douchi or Chinese salted black beans or even the black soybean should not be confused with black turtle bean, a variety of common bean that is commonly used in the cuisines of Central America, South America, and the Caribbean.
It is used as an ingredient for mapo tofu. Douchi is also used to flavor fish or stir-fried vegetables. Unlike some other fermented soybean-based foods such as natto or tempeh, douchi is used only as a seasoning, and is not meant to be consumed in large quantities, being typically much more salty.
Some common dishes made with douchi are Steamed Spare ribs with Fermented Black Beans and Chili Pepper, and Braised Mud Carp with Fermented Black Beans.