Process steak until mixture resembles mince. Heat oil in a large frying pan over medium-high heat. Add onion and bacon. Cook, stirring, for 3 minutes or until golden. Add mince. Cook, stirring with a wooden spoon to break up mince, for 6 to 8 minutes or until browned.
Add tomato paste and flour. Cook, stirring, for 1 minute or until combined. Add stock and thyme. Stir to combine. Bring to the boil. Reduce heat to medium-low. Simmer for 30 minutes or until sauce has thickened and meat is tender. Season with pepper. Remove from heat.
Preheat oven to 200°C/180°C fan-forced. Line eight 7.5cm round pie moulds with shortcrust pastry. Trim excess. (I would bake the crust for 5-8 minutes before filling with meat mixture to have a flaky crust) Fill cases with steak mixture. Top with puff pastry. Trim excess. Press edges together with a fork to seal. Using a small sharp knife, cut a small cross in pie tops. Brush with egg. Bake for 25 to 30 minutes or until golden. Serve with sauce.