Soak kombu in 1litter water and leave for a night. (kombu water).
Soak dried shiitake in 200ml water for a night. (shiitake water). And take shiitake out from shiitake water, slice thin.
Place kombu water, shiitake water, mirin and light soy sauce into the pot and bring to boile.
Take kombu out from pot and add 10g bonito flake. Turn off the heat and leave 5 minutes.
Strain the #1 udon dashi. Place #1 udon dashi into the pot and heat, add salt to taste. Bring to the boile and add bonit flake. Turn off the heat and leave 5 minutes.
Strain #2 Udondashi and add sliced shiitake.
Boile soba noodles for 5minutes and strain, wash and rinse in cold water. Strain and through into udon -dashi pot, bring to the boile.
Palce cooked soba and dashi into the bowl and put wakame and scallion as garnish.