Crush the peppercorns with the mustard, rosemary, celery seeds and a little salt using a pestle and mortar. Blitz the mushrooms to a fine powder in a food processor, then stir them in with 2 tbsp oil and rub all over the beef. Cover and chill for at least 1 hr, but overnight is best.

Heat the slow cooker to high and pour in the stock. Heat 2 tbsp oil in a large pan and brown the beef, then put in the slow cooker skin-side up. Fry the carrot, onion and celery in the same pan over a medium-high heat for about 10 mins. Stir in the tomato purée and wine, scraping the bits off the bottom of the pan, then add this to the slow cooker.

Cook on low for 6 hrs, then strain the liquid into a pan. Keep the meat and veg covered with foil so they stay warm. Bring the liquid to the boil, then simmer until reduced by a third and season. For thicker gravy, mix the cornflour with 2 tbsp water and whisk into the boiling liquid. Serve the beef with the gravy, along with some mash and greens.