A simple clear soup with Kombu sea kelp and Katsuobushi bonito flakes, seasoned with soy sauce and Sake
Put water and Kombu in a pot and heat at medium heat until just before boiling. Remove Kombu. Add Katsuobushi and let the water boil then immediately turn off the heat. Leave it for 5 minutes and strain.
Season Dashi broth with Soy Sauce, Sake, and salt.
Cut Tofu into 1/2" cubes and chop Mitsuba coarsely.
Add Tofu into the soup and cook for a minute. Pour the soup into a bowl and sprinkle Mitsuba.