Using a meat grinder or an electric mixer fitted with a medium coarse die, grind the meat and fat together. In a mixing bowl, combine the ground meat, onions, garlic, salt and pepper. Mix well, cover and refrigerate overnight.

Place the potatoes in a medium bowl and cover with water, cover and refrigerate overnight.

Combine the meat and potatoes together and mix well.

In a mixing bowl, combine the flour and salt. Mix well. Add the shortening and mix until the mixture resembles coarse crumbs. Add the water and let sit for 1 minute. Using either a fork or your hands, carefully press the mixture together forming a soft ball. Wrap in plastic wrap and refrigerate for at least 30 minutes. Remove the dough from the refrigerator and place it on a lightly floured surface. Cut the dough in half and roll the dough out on the floured surface into a circle about 12-inches in diameter and 1/8-inch thick.

Preheat the oven 350 degrees F.

Gently fold the circle of dough in half, and then in half again so that you can lift it without tearing it, and unfold into a 9 by 2-inch deep-dish pie pan. Spoon the meat mixture into the pie crust. Brush the edges with the beaten egg. Lay the second pie crust over the meat mixture. Crimp the edges and place in the oven. Bake for 30 minutes. Reduce the heat to 300 degrees F and continue to cook for 1 1/2 hours.

Remove from the oven and cool for 10 to 15 minutes before serving. Slice the pie into individual serving. Garnish with parsley