Coat a small non-stick skillet with a layer of cooking spray on medium-low heat.
Whisk together egg and liquid egg whites.
Pour in egg mixture and season with salt & pepper and cover immediately (do not scramble).
Allow eggs to cook for 2-3 minutes or until set on the bottom.
Use a spatula to flip the eggs (like a pancake) and cook through for another minute.
Remove from heat and set aside on a plate.
Season mashed avocado with salt & pepper and add in the already cooked quinoa or rice, stir to coat. Add on top of omelet.
Top with cherry tomato halves and scallions for garnish.