Personally, I think it takes 24 hours to cook dried kelp. The water for soaking dried kelp need not be dried kelp. It is suggested to use warm water to shorten the soaking time. After kelp is dried and soaked, the surface of kelp is rubbed to remove impurities, and finally it is washed with clear water before cooking. When cooking kelp, it is best to put it in a pot with cold water. Adding a little vinegar to the pot can accelerate the ripening of kelp.