Roll the pie dough into 2 flat pieces, place them on an ungreased cookie sheet; brush with a little milk. Bake in a 425 degrees F oven until brown. Cut the crust in squares; set aside.
Cut beef into bite-size pieces. Place in a large casserole. Chop the onions and add to the meat. Add bay leaf and fresh ground pepper (no salt at this stage). Add cold water just to cover. Cook in a 350 degrees F oven until the meat is fork tender, about 2 hours. During the cooking process let the water cook down so the meat will brown, and then add more water so that when the meat is done, you have about 3 cups of liquid. When the meat is done, remove the bay leaf; thicken liquid with a flour paste to make a gravy.
While meat is cooking, peel and cube the potatoes, boil till tender, and drain. When meat and gravy are ready, add the potatoes and salt to taste and reheat all together in the oven till bubbly.
Spoon the stew into deep plates and pass the piecrust squares, which should be crumbled over the top of each serving right before it is eaten.