Preheat oven to 425°.
Combine the dressing and egg whites in a small bowl, and stir well with a whisk. Combine the cornmeal, cheese, flour, pepper, and salt in a shallow dish. Dip fish in egg white mixture; dredge in cornmeal mixture.
Place fish on a baking sheet coated with cooking spray; bake at 425° for 12 minutes on each side or until lightly browned and fish flakes easily when tested with a fork. Serve with lemon wedges.