Put milk, lemon peel, and cinnamon in a saucepan and bring to the boil. Lower the heat and simmer for ten minutes. Set aside. In another saucepan beat the egg yolks until lemon-coloured, then beat in the cornstarch. Stir in a few tablespoons of the hot milk mixture, then gradually stir in the rest. Cook over a moderate heat, stirring constantly, for about four minutes or until thickened. Discard the lemon peel and cinnamon stick. Pour into a large greased, rectangular pan and leave to cool. Then refrigerate this for several hours or overnight. Once set, cut it into small squares, dust each square with flour, and dip them in the egg mixture. Heat the oil and fry the squares until brown on all sides. Drain. Dust with a mixture of sugar and cinnamon. Just before serving, sprinkle with powdered sugar. If you wish, serve with strawberry jam.