For the salad:
For the sauce:
Bring a large pot of water to a hard boil and cook the soba noodles, stirring often, until al dente, just about 3 minutes. Quickly strain and rinse in cold water until cool.
In a large mixing bowl, combine the cooled soba with the rest of the salad ingredients.
Combine all of the ingredients for the sauce in a blender or bowl and mix thoroughly then add to the soba salad and mix and massage the sauce into the salad until well dressed. Chill thoroughly before serving and garnish with thinly sliced radish and shaved scallion if desired. Alternatively, arrange the soba noodles and salad components artfully in a bowl and add the sauce just before serving. Any remaining soba noodles will keep covered in the refrigerator for up to 3 days.