To make a great potpie, the meat has to be cooked long and slow. You want it to be moist and succulent, so only use beef that has plenty of sinew and a little fat. Then the pieces of meat will stay together and not be stringy. The filling is just as good on thick slices of hot, buttered toast.
Shake the meat and the flour in a plastic bag with some salt and pepper, a quick way to coat the meat in flour with no mess.
Heat a Dutch oven over medium heat and add the oil. When hot, fry the onions for about 3 minutes. Add the floured meat and cook until colored, about 10 minutes. Pour in the stock (or water) and add the Worcestershire sauce. Bring to a boil, then reduce the heat to a simmer and cook for about 2 hours.
Add the potatoes and cook gently for 1 hour longer.
Meanwhile, make the pastry: Rub the lard into the flour and salt, or mix in a food processor, until resembling bread crumbs. Add the water bit by bit and mix to a dough. Let rest for 20 minutes.
Check the meat: when ready it will be soft and break apart when squeezed. The sauce should be rich and thick. Season with salt and pepper as necessary.
Heat the oven to 375°F. Select a deep baking dish that has a rim. Fill the dish three-quarters full with the meat mixture. Roll out the pastry to 1 inch thick and cut into a shape large enough to cover the top of the dish. Beat the egg and milk together and brush over the rim of the dish. Lay the crust over the dish and press the edges down firmly onto the rim to seal. Brush the crust with the egg wash, then cut a small hole in the middle to allow steam to escape. Bake for 40 minutes. If the edges of the crust become too brown during baking, protect with some foil.
Photo: Jason Lowe