Heat oil in a heavy pot. Brown the beef in batches, 3 minutes per batch. Set aside.
Cook onion 5 minutes. Add garlic, tomato paste, Worcestershire, Vegemite. Stir 60 seconds.
Return beef. Add stock. Bring to a simmer. Cover. Simmer 1.5 hours until beef is tender.
Whisk flour with cold water in a small bowl until smooth. Stir into the simmering pot. Cook 5 minutes until thick. Cool completely.
Preheat oven to 200°C fan.
Cut shortcrust to fit pie tins. Fill with cooled beef mixture. Top with puff pastry. Crimp edges. Egg wash.
Cut a small steam vent in each top. Bake 25-30 minutes until puffed and deeply golden.
Serve with tomato sauce. Or HP. The eternal debate.