Some good Japanese miso soup recipes include the Food Network's miso soup, authentic miso soup on Allrecipes and miso soup on the Japanese Cooking 101 website. The recipes call for tofu, dashi and miso.
To make the Food Network's miso soup, wrap a 12-ounce block of firm silken tofu in paper towels, place it between two plates, and put a 28-ounce can on top of it for 20 minutes. Meanwhile, pour 2 quarts of dashi into a saucepan, and heat at medium-high heat until it reaches a temperature of 100 degrees Fahrenheit, and then remove 1 cup.
While simmering the rest of the dashi for 10 minutes, whisk the removed 1 cup of dashi with 6 tablespoons of dark or red miso and 2 tablespoons of light or white miso until a smooth liquid is formed. Add the miso mixture to the simmering dashi, and bring everything back to a simmer. Cut the tofu into 1/4-inch cubes, and add it and 4 thinly sliced scallions into the mixture. Cook the soup for a minute longer, and then serve it.
Make a simple miso recipe by boiling 4 cups of dashi and adding 1 package of cubed tofu to the liquid before turning the heat to low. Dissolve 4 to 5 tablespoons of miso paste into the simmering broth, and add 2 finely chopped green onions.