In boiling water, cook Aburaage for a few seconds to cut grease and drain.
In a pot, put the rest of the ingredients for "Kitsune," heat at medium heat, and add prepared Aburaage. Cook until all the liquid is gone. Set aside.
Heat Dashi to a boil, and add salt, Soy Sauce, Mirin, Sake.
Add Udon to the soup and let it simmer for 2-3 minutes.
Divide noodles and soup into bowls, place cooked Aburaage on top, and sprinkle on the chopped green onion. Add Shichimi if you like.