Heat oil in a large flameproof casserole dish over medium-high heat. Cook steak, in batches, for 5 minutes or until browned on all sides. Transfer steak to a plate.
Add butter to dish with bacon, onion and mushroom, then cook for 10 minutes or until golden. Add garlic and cook for 1 minute or until fragrant. Stir in tomato paste, then sprinkle flour over mixture and stir until well combined. Slowly add stock, stirring constantly, until well combined. Bring mixture to the boil. Return steak to dish and return to the boil. Cover with lid and bake for 11/2 hours or until beef is very tender. Season. Scatter over parsley and serve with mashed potato and green beans.