rib of beef, trimmed, weight 3-4kg/ 6lb 8oz-8lb 12oz, 3-bone
100ml/3½fl oz sunflower oil
4 carrots, peeled and halved lengthways
85g/3oz demerara sugar
85g/3oz wholegrain mustard
Remove the beef from the fridge first thing in the morning, to allow it to come to room temperature. Heat oven to 220C/fan 200C/ gas 7. Rub beef all over with oil and season with salt and pepper. Put the carrots in the roasting tray, then sit the beef on top. Roast for 20 mins. Reduce the temperature to 160C/fan 140C/gas 3 and roast for a further 40 mins/kg or 18 mins/lb for medium rare.
Mix the sugar and mustard together. Half an hour before the end of cooking, spread the mixture over the beef and continue to roast. The sugar will caramelise to a lovely golden brown, then harden to form a crispy layer once out of the oven. Remove the beef from the oven and leave to rest for 20 mins before carving. You can roast the beef in the morning, carve and arrange the slices on a platter, then serve at room temperature.