To a food processor add the flour and salt and butter.
Pulse until you get the texture of fine breadcrumbs.
With the processor running, slowly drizzle in cold water until it forms a ball.
Turn the dough onto a floured surface and shape into a flat ball.
Wrap in plastic wrap and refrigerate 10-15 minutes.
Preheat oven to 360°F.
Whisk the egg with the milk.
Take 4 ounces pastry and roll into an 8 inch circle.
Place a small handful of potatoes, rutabaga, onion, and beef in the center of the pastry, leaving 2-inch border.
Sprinkle with a small amount of salt pepper and flour. Place a little piece of butter on the top.
Brush half of the edge of the pastry with egg mix then fold the pastry in half and seal the edge.
Twist the edge to create a good seal.
Cut a slit in the top of the pasties and place onto a parchment lined baking sheet.
Brush all the pasties with the rest of the egg/milk and bake for 45 minutes until golden brown.