Miso Soup Miso soup is a traditional Japanese soup consisting of a stock called "dashi" into which is mixed softened miso paste. Although the suspension of miso paste into dashi is the only characteristic that actually defines miso soup, many other ingredients are added depending on regional and seasonal recipes, and personal preference. Miso is soy bean paste, which is an essential condiment in Japanese cooking. Miso is made by fermenting soy beans with salt and koji. Koji are fermented grains such as rice, barley, and soy beans. Solid Ingredients According to Japanese custom, the solid ingredients are chosen to reflect the seasons and to provide contrasts of color, texture, and flavor. Thus negi and tofu, a strongly flavored ingredient mixed with a delicately flavored ingredient, are often combined. Ingredients that float, such as wakame seaweed, and ingredients that sink, such as potatoes, are also combined. Ingredients can include mushrooms, potatoes, seaweed, onion, shrimp, fish, and grated or sliced daikon.