This following is from Wikihow:
Miso soup is very popular in Japan and within the Pacific Region. It has also become a staple meal within the Japanese culture. Korean restaurants serve a similar, but different tasting, soup.
* 1⁄4 oz (7 g) dried seaweed (wakame)
* 4 1⁄4 oz (120 g) fresh soft tofu or long life silken tofu
* 13 1⁄2 fl oz (400 ml) dashi (fish and seaweed stock) or 400 ml (13 1⁄2 fl oz) of water and 1⁄2 tsp (2.5 ml) powdered dashi
* 1 1⁄2 Tbsp (20 ml) miso paste
* 2 medium spring onions
1. Heat the dashi. Pour the dashi into a large saucepan or pot, place it on the stove, and turn the heat onto "high".
Soak the wakame. Place the seaweed into a small bowl and add water into the bowl, until it covers it well. By doing this, you're expanding the seaweed.
Melt the miso by putting it into a cup, and pour a little bit of dashi on it to melt it down. Stir throughly until the miso is dissolved. Pour the mixture into the pan and stir.
4. Cut the tofu into into 1 cm squares. You may cut it however you like, bigger or smaller, than 1 cm (depending on your style or likings). Add the tofu pieces to the pan and turn the heat down.
5. Add the wakame to the pan. You do not want this to boil, as the flavors of the dish may impair or distort.
6. Serve the miso soup in bowls. Chop up the spring onions and garnish each bowl before serving.