Combine the first 6 ingredients in a large bowl. Stir in the beaten egg whites. Heat 2 teaspoons vegetable oil in a large nonstick skillet over medium heat. Spoon 4 (1/2-cup) potato patties into the skillet, and flatten slightly with a spatula; sauté for 7 minutes. Carefully turn the patties over, and cook for 7 minutes or until patties are golden. Repeat the procedure with 2 teaspoons vegetable oil and the remaining potato mixture.