For the ragu, heat the oil in a casserole or heavy-based, oven-friendly pan and fry the beef in batches until browned all over. Remove from the pan and set aside. Tip in the onion, carrot and celery, and fry for 15 minutes until soft and lightly golden. Stir the beef back into the pan with any resting juices. Add the tomato purée, herbs and wine. Bring to a simmer and cook until the liquid has reduced by half, scraping any bits that have stuck to the bottom of the pan. Pour in the stock to cover the meat, adding a splash more water if you need to. Cover with a sheet of foil, then put on the lid. Cook for 3-4 hours or until the beef is tender and falling apart. Remove the lid for the final 30 minutes to thicken the sauce if you need to. Shred the meat into the sauce with two forks and remove the herbs.