Soak the wakame in cold water for 5
minutes, or until rehydrated and glossy but not mushy. Drain
well, then divide among four small Japanese soup bowls or Chinese rice
bowls. Divide the tofu and the scallion among the bowls.
Pour the dashi into a saucepan and bring to the boil. Combine
the miso with 250 ml of the dashi stock in a bowl. Whisk until
smooth. Return the miso mixture to the saucepan and stir until
combined - be careful not to boil the broth as this will diminish the
flavor of the miso. Ladle into the bowls until they are
two-thirds full. Serve immediately. Sip the miso soup from
the bowl - rest the bowl in your left hand and tilt to your lips with
your right. You can use chopsticks to eat the solid ingredients.