Drizzle some olive oil on a skillet. Add chopped onions and cook on medium-high heat until soft and translucent.
Add diced tomatoes (including all the juice) and 1 tsp sugar. Allow to boil for 15-20 minutes or until all the liquid is gone and the mixture is well caramelized (see note 3).
Meanwhile, season eggs with salt and pepper. Switch to low heat and pour the eggs into the caramelized onions and tomatoes. Stir continuously so that the eggs incorporate into the onions and tomatoes well (we don't want them cooking separately).
Once cooked (still juicy and not dry), take off the heat and add feta cheese. Stir until combined.
Chopped, you should have a heaping 1 1/2 cups - 2 cups of onions.
You can also use canned, diced tomatoes. Make sure to include the juice.
Add 1/4 cup water if your tomatoes are not very juicy.