Combine the flour and the salt in the bowl of a food processor or a large bowl, add in chilled cubed butter and lard and either process in a food processor or cut in with a pastry blender until you have fine crumbs. Add in beaten egg and ice water and pulse in a food processor for about 20 seconds until you have a dough ball stuck around the centre of the processor. Take it out of the food processor and separate 1/3 of the pastry. Shape each piece into a ball and then into a flat disk, wrap into plastic wrap and keep in the refrigerator while you are dealing with the apple filling. (The pastry could be made a day ahead.)
Peel, core and slice the apples thinly. In a large bowl, toss the sliced apples with brown sugar, cinnamon, mixed spice or nutmeg and flour.
On a floured surface roll out the bigger pastry piece into a circle large enough to line the bottom of a 9 inch pie plate with an overhang. Then roll out the second piece of the pastry to cover the top of the pie and move on to the filling.
Add the apple filling to the lined with pastry pie plate and scatter little dots of butter all over. Cover with the top piece and trim the excess pastry. Pinch the sides of the pie to seal and cut slits on the top. Brush with a beaten egg all over for a golden finish. You may roll out the excess pastry and cut decorative apples, leaves or anything you like with a cookie cutter. Apply on the surface of the pie and brush with the egg wash, then sprinkle with the sugar all over.
Bake at 375F/190C for 60 minutes or until the pastry is golden and the filling is bubbling through the slits.