1. In pie plate or shallow bowl, combine KELLOGG'S CORN FLAKES cereal, garlic salt and oregano. Place flour in second pie plate or bowl. Set aside.
2. In small bowl, beat egg whites and water with fork until thoroughly combined. Set aside.
3. Peel onion and cut into 1/2-inch thick slices. Separate slices into rings. Dip onion in flour, then in egg mixture, then cereal mixture. Carefully repeat dipping in egg mixture and cereal mixture to double coat completely. Place in single layer on foil-lined baking sheet coated with cooking spray. Lightly spray coated onion rings with cooking spray.
3. Bake at 400° F about 8 minutes or until onion rings are tender and lightly browned. Serve hot.