Prep everything before you start cooking.
Wipe the mushrooms clean and slice thick (about 3 to 4 slices per mushroom).
Beat the eggs with the lemon pepper and water.
Grate the cheese.
Heat the olive oil in a skillet and sauté the mushrooms until they are golden brown.
Remove the mushrooms from the pan and keep warm.
Pour the eggs into the hot pan and cook on low until the eggs start to set. Gently lift the eggs with a large spatula and flip.
Place the mushrooms and cheese on top of the omelet and continue to cook until the cheese starts to melt.
Fold the omelet and cut in half. Place each piece on a plate and garnish with green onions.