Lightly beat the eggs in a bowl. Finely chop Mitsuba leaves or green onion. Grate ginger root. Set all aside
Prepare Dashi using a Dashi packet. Season the Dashi with salt, soy sauce, Sake, and Mirin. Make a slurry with potato starch and water, add it to the soup, and stir well until it begins to thicken. Stir in grated ginger and sesame oil.
While the sauce is boiling, gently pour in the beaten eggs in a swirling motion. Once the eggs turn fluffy.
Place steamed rice in bowls, pour the egg sauce over it, and top with the chopped Mitsuba leaves.