Soak mushrooms in hot water 45 minutes; drain.
Coarsely chop, and set aside.
Coat a small skillet with cooking spray.
Place over medium heat until hot.
Add mushrooms and green onion, saute until render.
Stir in sherry, Worcestershire sauce, and pepper cook over medium heat 1 minute or until liquid is absorbed.
Transfer mixture to a small bowl; set aside, and keep warm.
Combine eggs, egg whites, milk, and white pepper in a small bowl; beat well and set aside.
Coat a 10-inch nonstick skillet or omelet pan with cooking spray; place over medium heat until hot enough to sizzle a drop of water.
Pour in egg mixture.
As mixture begins to cook, gently lift edges of omelet with a spatula, and tilt pan to allow uncooked portions to flow underneath.
When egg mixture is set, spoon reserved mushroom mixture over half of omelet loosen omelet with spatula, and carefully fold in half.
Carefully slide omelet onto a warm serving platter, garnish with chopped parsley.
Cut omelet in half, and serve immediately.
Garnish each serving with a tomato rose, if desired.