Douchi 「豆豉」or also known as Chinese fermented black beans is a unique seasoning widely used in Chinese cuisine. It is a fermented food made from soy beans, almost with yellow soy beans and sometimes black beans too. The "black" is actually describing the color presented after drying.
Douchi has a very long history in Chinese cuisine. There are records showing how to naturally make douchi in Han dynasty. With such a long history, dou-chi has been find different roles in several Chinese cuisines. Among those cuisines, Sichuan cuisine and Cantonese cuisine love to use douchi the most frequently.
How Douchi is produced?
Douchi will go through two stages of fermentation. Soy beans are firstly soaked until soft and then steam until almost cooked. Then the beans are then naturally fermented by microbial or by kit starter to import Aspergillus oryzae. Yellow hair grows in the process. We wash the hair because it contains bitter taste and then transfer the beans to jar for months long fermentation (this is the second fermentation stage). Along with the time, soy sauce and fermented beans are presented. This lovely stage is called as watery douchi (水豆豉). The fermented beans are further dried (either by sun or a dryer) in order to get a denser and more profound flavor. If you are interested about the process, check Doubanjiang. They share very similar process.
Since it goes through long time of fermentation, douchi has a salty, pungent yet aromatic taste. It tastes a little bit salty when eating raw but douchi should be used as condiments in dishes or mix with other ingredients to make a sauce or paste.
Basic douchi contains only soy beans, mold or starter and salt. But there are also brands may use some spices like chili powder or five spice powder. 
Like other fermentation food like natto, douchi contains lots of beneficial amino acid that can be good for our healthy. But it contains lots of sodium and thus spare the amount.
Douchi can be used directly in dishes. Lots of Sichuan dishes (mapo tofu, twice cooked pork belly) call for douchi, not as a main seasoning, but it do improve the flavors and taste a lot.
Douchi can be used to make sauce or paste too. There are several famous sauce brands using douchi to make lovely instant eating sauce like crispy chili with douchi from Lao Gan Ma. Douchi sauce from Lee Kum Kee.
Sometimes, douchi can also carry the main roles, in most cases with garlic to make yummy steamed dishes or douchi flavor stir fries including douchi steamed chicken. Check the following recipe ideas for more inspirations.
There is no need to rinse douchi before using if the amount is well controlled. But for those who need special watch on sodium take in, rinsing is optional.
Most of the asian store sell douchi or try to get it from Amazon.
Douchi is usually packaged in plastic bags, once opened, transfer them to an air-tight container and keep in fridge. Well stored douchi can be kept for six months.
Douchi Recipes
Douchi, fermented black beans can be used to make directly use sauce. Following is black bean and garlic sauce and another is spicy douchi sauce.
Black beans can also be used in stews, soups, steamed dishes and stir frying. Following is some of the most popular dishes using douchi as the main seasoning.
In lots of Sichuan dishes, dou-chi is also used as a side seasoning in addition to doubanjiang.
Jen
I recently developed an allergy to capsicum-bell peppers (all colors), chilies, and paprika. I miss eating fermented black bean dishes. Which brands are available without chili peppers or other capsicum as ingredients. Thanks!
Elaine
Jen,
I am not sure which type qualifies. But why not choosing to make Black Bean Sauce with garlic, ginger and shallots only at home?