Make the shortcrust dough: Add flour and salt to a mixing bowl. Cut in shortening and butter until well combined. Stir in 5 Tbsp of water then add 1-3 more tablespoons as needed till dough binds together and is not dry. Be careful not to over mix.

Divide the dough into two balls and form each into a log. Wrap them in plastic wrap and place chill in the refrigerator for 20 minutes.

Prepare the filling: Cut the steak into bite size cubes, and chop the potatoes, rutabaga, onion. Add steak, vegetables, thyme, rosemary, garlic powder, salt, and pepper to a bowl and toss.

Preheat the oven to 350 degrees F.

Roll the Dough: Take one dough disk out of the fridge, leaving the other to continue to chill while you make the first four pasties. Cut the log into 4 equal pieces. Place one piece at a time on a large piece of parchment paper sprinkled lightly with flour. Roll the dough into a thin circle about 7-8 inches across. Don't worry if your circle isn't perfect as you will be folding and crimping the edges.

Add filling: Place a heaping spoonful of filling into the center of the dough. Cut off a sliver of butter and place it on top of the filling.

Fold and seal edges: Lightly moisten the edges of the pastry dough with a little bit of water (use a pastry brush or your finger). Gently lift the dough on one side and bring it over the filling, laying it on top of the dough on the other side. If the dough punctures at all, use any extra dough to patch the hole. Squeeze the edges of the half circle of dough, pressing them firmly together.

Crimp the edges of the dough: Push down on the edge of the pasty and using your index finger and thumb twist the edge of the pastry over to form a crimp.Repeat this process along the entire edge. Tuck the end corners underneath. Lay the cornish pasty on the baking sheet and repeat with remaining dough. When you've crimped all four pasties, remove the remaining dough from the fridge and repeat process.

Add egg wash: Lightly prick the top of each pasty with a fork (2-3 times) for air to escape. Mix egg and water in shallow dish for the egg wash and use a pastry brush to apply a thin layer on top of each pasty.

Bake at 350ºF for 40-50 minutes or until golden. Allow to cool for 10 minutes before eating.