Douchi is a type of food that is made from soybeans. First, the soybeans are cooked until they are very soft. Then, they are mixed with a special kind of mold called Aspergillus oryzae. This mold helps the soybeans to ferment, which means they start to break down and change in a special way. This process takes several days, and during this time, the soybeans acquire a strong, salty flavor. Once the fermenting process is complete, the soybeans are dried out and become very hard.
People use douchi to add flavor to their dishes. You can think of it like a kind of flavoring, like salt or pepper. Some people like to add douchi to soup or stir-fry dishes. It's important to remember that douchi has a very strong taste, so you might not like it if you haven't tried it before. But for many people, adding douchi to their cooking is a delicious way to make their meals more flavorful.