Cut napa cabbage into 2" pieces, wash throughly.
Mix sugar, vinegar, tamari, sesame oil, and oil in a glass measuring cup. Add a little cornstarch, mix until throughly blended.
Saute garlic and fresh grated ginger in some oil in a big pot. Add the cut cabbage. Stir until the cabbage is wilted. Scoop out excess liquid from the pot. Add sesame seeds.
Pour the sauce over the cabbage, cook until glossy and thickened.