Prep Time: 10
Cook Time: 12
Serves: Serves: 1
Coat large non-stick skillet with cooking spray. Cook onion over medium heat 4 minutes, stirring occasionally. Add tomatoes and 1/8 teaspoon salt; cook 2 minutes. Transfer mixture to small bowl; set aside. Wipe out skillet; coat with cooking spray.
Beat together egg whites, egg, 1 tsp.water, remaining salt, oregano and pepper in medium bowl; pour mixture into skillet. Cook over medium heat 2 minutes or until bottom is set.
Spoon onion mixture over one half of egg mixture; top with cheese. Fold omelet in half; cook 2 minutes or until cheese is melted.