Coat meat with flour, shaking off excess. Heat oil in a heatproof casserole dish over medium heat. Cook meat, in batches, for 3-4 minutes each side or until well browned, adding more oil as required. Transfer to a plate. Preheat oven to 180°C.
Add onion to same pan and cook for 4 minutes or until softened. Add garlic and cook for 1 minute. Stir in stock and sauces and bring to the boil. Return meat to pan with peppercorns. Cover and bake for 1 hour or until meat is very tender. Cool for 30 minutes.
Meanwhile, lightly grease 6 x 13cm round pie tins. Cut 16cm rounds from the shortcrust pastry and press into the tins. Cut 13cm rounds from puff pastry for lids. Keep bases and lids covered and chilled in the fridge.
Preheat oven to 200°C. Place a baking tray in oven. Fill pastry bases with meat mixture. Brush edges with water and top with pastry lids, pressing edges together using a fork to seal and trim excess. Brush pie tops with egg and make a steam hole using the point of a knife. Place pies onto hot baking tray and bake for 25 minutes or until pastry is golden and puffed. Serve immediately.