In a large bowl, combine 1/2 cup of tomato sauce, egg, 1-1/2 cups onions, parsley, salt, pepper and garlic powder. Crumble beef over mixture and mix well. Shape into a loaf in a greased 11x7-in. baking dish. Bake, uncovered, at 350° for 45 minutes; drain. Combine sugar and remaining tomato sauce; spread over the meat loaf. Sprinkle with remaining onions. Place carrots and potatoes around loaf. Bake, uncovered, 15 minutes more or until meat is no longer pink and a thermometer reads 160°. Let stand 10 minutes before slicing.