Heat oven to 350F.
In a large bowl, combine the beef, potatoes, onions, 1 teaspoon salt and ¼ teaspoon pepper.
Place the flour, butter and 1 teaspoon salt in a large bowl.
With a pastry blender or 2 knives, cut in the butter, working until the mixture resembles coarse meal, with a few pea-size lumps remaining.
Add ⅔ cup ice water; mix with a fork and work with your hands until a dough comes together.
If the dough is still crumbly, add more ice water, 1 tablespoon at a time (up to 4 more tablespoons). Do not overwork.
Shape the dough into 4 small disks and let rest for 10 minutes.
On a lightly floured surface, roll each disk into a 10-inch circle.
Divide the beef mixture among the circles of dough, shaping the meat into a small loaf.
Gather and pull up the sides of the dough around the filling, pressing the edges together to form a seam on top.
Using your fingers, crimp the seam.
Transfer the pasties to a parchment-lined baking sheet.
Bake until golden brown, 1 ¼ to 1 ½ hours.
