Heat 1/2 tsp olive oil in a non-stick saute pan.

Add mushrooms and asparagus and saute for 3 minutes.

Combine onions, tomatoes, salsa, and cornstarch dissolved in water to form a sauce.

Heat remaining oil in a second non-stick saute pan.

Add egg substitute, cheddar cheese, garlic, Worcestershire sauce, celery salt, cider vinegar, salt, and pepper.

Cook until the egg is almost set.

Spoon the mushroom mixture onto half of the omelette.

Fold the other half over the mushroom mixture.

Cook for another 3-5 minutes.

Lift the omelette with a spatula onto a serving plate.

Sprinkle with cheddar cheese and serve immediately.