4 tsp extra virgin olive oil
1 small onion, finely chopped
Salt
1 10-oz pkg frozen chopped spinach, thawed (with all excess water squeezed out)
4 plum tomatoes, finely chopped (about 1 ½ cups)
Freshly ground black pepper
12 egg whites
2 tbsp water
Nonstick cooking spray

In a skillet or pan, heat oil over medium heat. Add the onion and a pinch of salt and cook for 3 to 5 minutes or until onion is softened. Add the spinach, cook and stir until hot. Add the tomatoes and pepper to taste and cook and stir for 1 minute. Remove from heat, cover and keep warm.

In a medium bowl, whisk the egg whites, water and a pinch of salt until frothy.

Lightly coat a medium nonstick skillet or omelet pan with cooking spray and heat skillet over medium heat. Add one-fourth of the egg white mixture, swirling to evenly cover the bottom of the pan. Cook for 1 ½ to 2 minutes or until set, using a rubber scraper to lift eggs up occasionally, letting runny egg flow underneath.

Spoon one-fourth of the spinach mixture onto half of the omelet, fold over and slide onto a plate. Repeat with remaining egg whites and spinach mixture to create four omelets.