Mix all-purpose flour, baking powder, and egg yolk in a large bowl.
Pour cold water into the mixture and stir until dough forms.
Sprinkle salt on top of the dough and add cubed butter or margarine. Knead until smooth.
Refrigerate dough for 30 minutes while preparing filling with diced potatoes, onions, skirt steak, swede, and unsalted butter.
Preheat oven to 375°F (190°C).
Roll out dough on a floured surface into thin pieces. Cut into four equal pieces.
Place filling on one side of each dough piece and fold the other side over, pressing down the edges to seal.
Brush beaten egg over pasties before baking for 40-45 minutes.
Let cool before serving and enjoy!