Miso is a fermented paste made by inoculating a mixture of soy beans, grain (like barley or rice), and salt with koji (a mold). It's a key ingredient in Japanese cooking and has a texture similar to peanut butter. It should be dissolved in water before using or it may remain in chunks, which can be very unpleasant to bite into!u003cbr/u003eMiso adds an umami flavor, and earthy taste to this soup. It is, however, a high sodium food and should therefore be used sparingly.