Heat a small skillet over medium-high heat. Whisk together eggs and a small amount of water to make mixture lighter. Set aside.

Chop mushrooms, onions, and green pepper.  Spray pan with cooking spray and add veggies; sauté 2 minutes, pour into a bowl and set aside.

In same pan, pour 1/4-1/2 egg mixture (use less with a smaller pan and more with a larger pan); allow eggs to become firmer; add some veggies to omelet; sprinkle with cheese.

Carefully flip half of the eggs over the veggies and cheese, into an omelet; allow to cook 1-2 minutes longer. If your pan is larger and you made 2 omelets per pan of eggs, cut it in half and serve each omelet topped with salsa, with mango.