Buy cowpeas and sun them first to remove some water. This way the pickled ones will be tasty. The specific time 3-4 days can be soaked, of course, this time is also related to the ambient temperature, generally speaking, summer is shorter than the time used in winter. Soaking cowpea water is actually very simple, boil the water, put in the right amount of salt, and then cool naturally. After cooling, put it and the sun-dried cowpeas into an altar with the mouth of the altar fastened with a bowl and pour some water to insulate it from the air. The first time will be longer, it will take about 10 days.