Douchi is made by using black beans or soybeans as the main raw materials, decomposing soybean protein with Mucor, Aspergillus or bacterial protease, adding salt, wine and drying to inhibit the activity of enzymes and delay the fermentation process. The earliest record can be found in Liu Xi's Interpretation of Famous Foods in the Han Dynasty, which praised Douchi as "the sum of five flavors must exist". The ancients not only used lobster sauce for seasoning, but also used it as medicine, and attached great importance to it.
Douchi is simple. After cooking soybeans in dog days, cover them with hemp leaves or plastic wrap for fermentation (to prevent water loss), and wait until a long layer of white hair or gray-black hair grows on soybeans (gray-black is a sign of the maturity of Mucor albicans, so it is safe to eat; But if you have yellow hair, it means that Aspergillus flavus can't be eaten. Then add salt and wine for sterilization, add some ginger and star anise, seal it, and you can eat it later. Stir-fry onions in oil when eating.
Douchi is a traditional fermented bean product in China. As early as the Han Dynasty, it was known as "blending five kinds of fermented beans with delicious taste and unique aroma." However, because of its rich nutrition, it is easy to deteriorate, and once it is stained with raw water, it is easy to get moldy. Therefore, it is best to seal it with ceramic utensils, so that it can be preserved for the longest time and the fragrance will not be emitted.