Sauce is a housekeeping food that Koreans can't live without for three meals a day. In Korean diet, there are many kinds of sauces, such as bean paste, soy sauce, Chili sauce and so on. Koreans also refer to soy sauce, Chili sauce and soy sauce as important "three brothers" in Korean recipes. Among the three brothers, soy sauce is the most special and nutritious. After buying soybeans, pick out beans with mildew spots. These beans contain aflatoxin which is carcinogenic. Then, after cleaning, soak them in clear water for one night, which is beneficial to precocity when cooking. When cooking, the soybeans should be cooked together with the soaked water, so as not to lose the taste and nutrition of the soybeans. When cooking, a lot of white foam will be produced and will be floated out. When the water is basically gone, the beans will be cooked and will not be burnt. Take out the cooked beans, wash them with clean water, and put them in a cloth bag to tie their mouths. After shaping, put it in a sunny place and a ventilated place for a few days. After drying the surface, it can be wrapped in paper and hung in a well-ventilated and sunny place for fermentation. The soy sauce blank can also be made into a square or round shape, weighing 35 Jin, or smaller, put in a cool and ventilated place, air-dry for three to five days, then tie the soy sauce blank with straw, hang it on the beam (or wrap it with white paper) and take it off for about 40 days.

Another layer of sauce blank and a layer of straw are placed at a suitable temperature and humidity to make them naturally ferment. (Generally, it is good to ferment when it is black inside.)

After several months, open the sauce blank, crush it (put it in a ventilated place to disperse the musty smell) and immerse it in light salt water. If the sauce blank floats on the salt water, it means that the concentration of the salt water is appropriate (you can put less salt water without soy sauce), and then soak it in salt water for about half a month, and it becomes a big sauce.

(After half a month of fermentation, take out the fermented sauce blank, and then boil the dark brown salt water to a certain concentration, which becomes soy sauce. This kind of soy sauce is sweet, salty and slightly bitter, and is mainly used for seasoning. )