What is the traditional method of making bean paste in China?

China's traditional method of soybean paste, is the first soybean soaking, steaming, mixing about 25% of the wheat flour made of "yellow steam" type of tune, mixing 15% to 20% of the concentrated brine, kneaded into a ball, placed in the sun half a month to two or three months, or stirred indoors for a few months to a year, so in a variety of microbial action, it becomes a unique flavor of the bean wheat paste. Under the action of various microorganisms, it has become a unique flavor of soybean wheat paste.

With soybean paste, soy sauce can be extracted from soybean paste by settling, filtering, washing or pressing. This kind of food method was already available in the Eastern Han Dynasty at the latest. In the Four People's Monthly Orders, it is mentioned that "clear sauce" is soy sauce.