In a bowl sift flour with salt. Make a well in the center and add the butter and lard cut into small cubes. Mix lightly with the finger-tips along with the iced water. Form into a smooth dough. Divide into 2 discs, wrap in plastic wrap and refrigerate for 1 hour.
Place all the meats through a fine mincer. Place the onion into a dry frying pan low heat and add the meat. Allow to fry gently in its own fat. When juices start top form in the bottom of the pan, season with the cinnamon, allspice, salt and pepper. Moisten the meat with water and cook very gently covered for 1 hour. Preheat the oven to 400 degrees. Cook potatoes in water. Drain and mash. Allow to cool. Add the meat mixture to the cold mashed potatoes and combine thoroughly. Season with more salt, to taste, if necessary.
Roll out 1 disc of dough and place in a 10-inch pie plate. Brush surface with egg white. Prick the base and fill with the meat mixture, packing down lightly and smoothing the surface. Roll out the other disc of dough. Paint the rim with egg white and place the pastry lid on top. Secure the edges by crimping them together. Paint the pie with egg yolk and bake for 40 minutes.