Basically, the rice malt which is produced from barley, soybean, rice and so on by a method similar to that of making soy sauce is immersed in salted water which is not so much as in soy sauce and matured.
醤油を作るときと同様の方法で麦・大豆・米などから製造した麹を、醤油のときほどは多くない塩水に漬けて熟成させるものが基本形である。