- Bring large pot of water to a boil over high heat, and cook noodles for 4 to 5 minutes.
- Drain and rinse under cold water.
- Bring 5 cups water to a boil over high heat.
- Slowly stir miso mixture into water.
- Reduce heat to medium; add mushrooms.
- When mixture returns to a boil, remove from heat and ladle soup into large soup bowls.
- Divide noodles, daikon and tofu into equal portions; add to bowls.
- Garnish with watercress leaves, nori and seasonings to taste.