Start by heating the olive oil in a non-stick skillet over medium heat.
Add the finely chopped onions and sauté until they become translucent.
Toss in the ground turkey. Break it apart using a spatula and cook until it turns brown.
Once the ground turkey is well-cooked, throw in the red bell pepper and mushrooms. Stir well.
As the veggies soften, sprinkle some salt and pepper to season.
In a separate bowl, crack open the eggs. Whisk them thoroughly until slightly frothy.
Pour the whisked eggs into the skillet, ensuring they cover the ground turkey and veggies evenly.
Let the eggs set for a few minutes. If using cheese, sprinkle it on top now.
Once the omelette begins to firm up, but still has a soft layer on top, flip it carefully.
Cook for an additional 3-4 minutes, or until fully set.
Garnish with fresh parsley and tomato slices.