1. Coat a 6-inch skillet with cooking spray. Place over medium-high heat until hot. Add zucchini and onions; sauté until tender. Add tomato; cook 1 minute. Transfer vegetables to a small bowl; cover, and keep warm. Set aside.
2. In a medium bowl, beat egg whites with a mixer at high speed until stiff peaks form. Combine egg substitute and next 4 ingredients in a large bowl. Fold egg whites into egg substitute mixture.
3. Wipe pan dry, and coat with cooking spray. Place over medium heat until hot. Spread half of egg mixture in pan. Cover; reduce heat to low. Cook 5 minutes or until puffy. Turn omelet; cook 3 minutes or until golden. Slide omelet onto a serving plate. Spoon half of vegetables over half of omelet; sprinkle with 2 tablespoons cheese. Fold omelet in half. Repeat procedure with remaining ingredients. Serve immediately.
carbo rating: 3