In a shallow dish stir together cornflake crumbs or crushed crackers, Parmesan cheese, garlic powder, and pepper. In another shallow dish beat together egg and water. Dip turkey steaks into egg mixture. Coat with crumbs.
In a large skillet cook turkey in hot margarine or butter over medium heat for 8 to 10 minutes or until brown and no longer pink in center, turning once.
Place lettuce on bottom halves of hoagie buns. Top with turkey, salad dressing, and tomato slices. Add bun tops. Makes 4 servings.