In a saucepan pour 2 liters water and add salt. When the water boils, add pre-cut potatoes into thin slices and chopped onions and peppers. Boil for 25 minutes and added well crushed with a fork feta cheese. Mix gently (care was taken not to crush potatoes) and boil for another 5 minutes. Thicken with yogurt, egg and a little lemon. Each serving sprinkle with fresh chopped parsley.