Place onions and olive oil in a skillet and cook until golden. Then add tomatoes and cook them for a couple minutes. Next, add three egg whites and let them cook until underside is golden. Slide omelet onto a plate. Invert skillet over omelet, then holding skillet and plate together invert omelet, brown side up, into skillet. Cook omelet until underside is cooked. Place omelet on a serving dish and add salt and fresh ground paper to taste. Add some chili pepper flakes or cayenne pepper to make it spicy.