Onion Rings

4 sprays cooking spray
2 large egg whites
1/2 c. fat free sour cream
2 large yellow onions sliced into 1/4 inch thick rounds and separated into rings
5 packets uncooked instant oatmeal
2 tsp. garlic powder
1 tsp. salt
1/2 tsp. dry mustard

Preheat oven to 400. Coat 2 large baking sheets with cooking spray. In a large shallow bow, whisk together egg whites and sour cream. Add onion rings and turn to coat. Transfer onion rings to a large bowl and set aside. In a small bowl, combine remaining ingredients. Sprinkle mixture over onions and toss to coat. Spread onions on prepared baking sheets and lightly coat with cooking spray. Bake until tender and golden, about 40-45 mins.