Thoroughly combine soy sauce, sherry, brown sugar, and ginger. Pour over potatoes and chicken in bakingdish. Cover and marinate 1 hour. Turn over chicken and potatoes and marinate additional hour.
Preheat oven to 325 degrees. Bake 25 minutes. Turn over potatoes and chicken; baste.Bake 30 minutes more. When no pink shows when chicken is poked with fork, remove dish from oven. Arrange potatoes around chicken on Servingdish. If desired, serve over rice. Sprinkle green onion for garnish.