1. Put pork, onion, allspice, cloves, salt, pepper, and 3/4 cup water into a wide, heavy pot. Break up meat with a spoon, then cook over high heat until water starts to boil. Cover and simmer on low heat for 1 hour. If mixture becomes dry, add a few tablespoons of water as needed.
2. Make pie crust while filling is cooking. Stir together flour and salt. Cut butter into flour mixture using a pastry cutter, or pulse butter and flour mixture in a food processor, until butter is the size of small peas. Stir in 1/2 cup ice water. Dough should look shaggy and come together when pressed into a ball. If it's too crumbly, add water by the tablespoon until dough just holds together but is not wet or sticky.
3. Divide dough in half. Flatten each half into a disk, wrap in plastic, and refrigerate.
4. After filling has cooked for 1 hour, peel and cut potatoes into 1/2-inch pieces. Stir potatoes into meat mixture. If mixture is dry, add 1/4 cup water. Cover and simmer over low heat for 30 to 35 minutes, until potatoes are tender. Uncover and cook off any excess moisture.
5. Remove from heat. With a potato masher, mash potatoes into meat. Set aside to cool to room temperature, 20 to 30 minutes.
6. While filling is cooling, preheat oven to 425 degrees F. Roll out both disks of dough. Line a 9-inch pie pan with one crust. Trim excess dough from edge. Refrigerate both crusts until ready to fill.
7. Prepare egg wash. In a small bowl, mix egg yolk with the water. Spoon cooled filling into bottom crust, pressing firmly.Brush crust edge with egg wash, then top with remaining crust, crimping edges to seal. Brush top of pie with remaining egg wash. Cut four 1 1/2-inch slashes into top crust. Bake in lower third of oven until crust is golden, 30 to 40 minutes. Servehot or at room temperature. Pie will keep 4 days, refrigerated. May also be frozen, wrapped in plastic, for up to 3 months.
Source: Hannaford fresh Magazine, May - June 2009