Microwave the turkey bacon strips for 3 minutes or until crisp. Set aside.
Whisk together the egg whites, salt, and pepper. Coat a nonstick skillet with cooking spray and heat the skillet. Add the egg white mixture. Cook and stir about 1 1/2 minutes or until the egg whites are set.
To serve: Spoon the egg whites onto the toast. Top with cheese, turkey bacon, and diced tomatoes.