Leave it in a warm place to let it rise for one hour. Then knead it again. Form small balls from the risen dough after dipping your hands in a mixture of the 2 types of fat, then arrange them in a greased tray. Again, leave for an hour to rise.
Once half risen, pour on the topping made from the set side flour, butter and 1/2 cup water. Sprinkle it with crumbled feta cheese and gently press to have it go in deeper. After the buns rise completely, spray them with the beaten egg and put them to bake in a moderately heated oven.