Heat the oil in a deep frying pan and sauté the onions for 6-7 minutes until wilted. Peel the tomatoes, remove the seeds and the excess juices, chop and put in the pan, together with salt and pepper and a bit of sugar.
Cook over a low heat for 20-25 minutes until the juices have completely evaporated and then add the eggs that you have previously whisked. Add salt and pepper.
Continue to cook, stirring all the while for 4-5 minutes until the eggs are cooked. Add the crumbled feta cheese and the slices of green pepper. You can serve it on toasted bread or rusks.