Preheat the oven to 180°C (fan), 200°C/Gas 6. Heat the oil or fat in a large roasting tin in the oven for 5 - 10 mins. Season the beef all over. Place the joint fat-side down in the roasting tin and put on the hob. Sizzle to release some fat, then turn the beef in the fat to seal and colour it all over. Turn the joint over and roast for 10-15 mins per 450g (Medium rare, 15-20 mins (medium), 20-25 mins 9medium-well done), 25-30mins (well done). Turn the joint halfway through its cooking time for an even roast.. Remove the beef from the pan, cover loosely with foil and rest for 15-20mins.