Spray a skillet with zero-calorie nonstick cooking spray. Add the asparagus, chopped onions, and diced tomatoes. Sauté for 5 mins. or until desired tenderness.
Add the crab meat and continue to sauté 5 more mins. or until the crab is cooked.
Whisk together egg whites, dill, onion powder, and pepper, set aside.
Spray a skillet with zero-calorie nonstick cooking spray. Add half of the egg mixture. Top the eggs with half of the crab mixture and allow to set.
Fold the omelet in half and press down with a spatula. When cooked on the side touching the pan, flip to cook the other side.