Spray small nonstick skillet with cooking spray; heat over medium heat until hot.
Cook and stir onion 2 minutes or until crisp-tender.
Add artichoke hearts.
Cook and stir until heated through.
Add spinach and tomato; toss briefly.
Remove from heat.
Transfer vegetables to small bowl.
Wipe out skillet and spray with cooking spray.
Combine egg substitute, olives and pepper in medium bowl.
Heat skillet over medium heat until hot.
Pour egg mixture into skillet.
Cook over medium heat 5 to 7 minutes; as eggs begin to set, gently lift edges of omelet with spatula and tilt skillet so that uncooked portion flows underneath.
When egg mixture is set, spoon vegetable mixture over half of omelet.
Loosen omelet with spatula and fold in half.
Slide omelet onto serving plate