In a large bowl whisk the eggs of foam. Mix yogurt and flour, add the eggs and again crashed. To the mixture was added to the cottage cheese, salt and pepper and stirred to obtain a homogeneous mixture. In a wide pan melt half the butter, add a little sunflower oil and pour the mixture. Fry was omelet, capped with a lid and turns with a wooden spoon. Cut onion into thin ribbons, put his little salt and crushed by hand, then fry in remaining butter. Serve the omelet as it put fried onions, tomato slices and chopped parsley.