Sift flour hill, on top of crumbled yeast, add a little sugar and warm milk, leave for 20 minutes. Mix with the remaining milk, sugar, salt, lard, eggs and lemon zest. Carefully interfere with the dough until it will not move away from the walls of the bowl. Leave for another 10 minutes. Roll out and cut into a rectangle again leave for proofing for 20 minutes. In a deep fryer or deep saucepan heat the oil, fry the donuts pieces until golden brown, put on paper towels, sprinkle with powdered sugar and serve.