For the dipping sauce combine soy, vinegar, and ginger. Set aside.
In a large bowl combine the grated potato with the other grated vegetables and ginger. Add scallions, the salt and pepper, and optional sesame seeds, if you want.Squeeze all the excess liquid from this mix using a colander, cheesecloth or your bare hands. Return to the bowl.
Mix in the eggs and panko bread crumbs. Form tablespoon= sized patties.
Heat a heavy gauge frying pan with a generous coating of oil. When a drop of liquid would sizzle in the pan, proceed to add a manageable number of the patties to the pan. As soon as the bottom of each turns golden brown, turn over. When golden on top, transfer to paper towels to drain.
Serve with the dipping sauce and sliced scallions. Pair these with sake if you like.