Bake the potato until done, 30 - 45 minutes in a preheated 400 degrees F (205 degrees C) oven. Peel and mash the potato.
Place the potato, ground pork, onion, spices and water in a large frying pan and simmer until very thick, for about one hour.
Meanwhile, prepare your pastry.
Line a deep-dish pie plate with pastry. Spoon in filling, spreading evenly. Cover with top crust.
Brush with beaten egg and sprinkle with paprika, if desired. Cut steam vent. Bake for 50 minutes at 350 degrees F (175 degrees C). If edges brown too fast, cover with a strip of foil. Serve warm.
