Roast beef & hasselback potatoes with chimichurri

Write down the beef joint’s weight (so that you can calculate cooking time later in the recipe). To get the best results, up to 24 hours before roasting, season the beef generously, rub all over with the oil, then return the joint to the fridge, loosely covered.

Take the beef out of the fridge 30 minutes before roasting. Preheat the oven to 220°C, gas mark 7. Put the joint in a large roasting tin and roast for 20 minutes, until well browned and sizzling.

Meanwhile, prepare the potatoes: sit a potato in a large serving or wooden spoon, then use a large knife to slice widthways at 3mm intervals. Cut down all the way until the knife hits the spoon (this will allow you to make deep slices without cutting all the way through the potato). Repeat with the remaining potatoes.

After 20 minutes, reduce the oven temperature to 180°C, gas mark 4. Lift the roasting tin out of the oven and baste the beef. Put the potatoes in the tin and carefully roll them to coat in the rendered fat, then sit with the slits facing upwards. Dot them with the cubed butter and season. Return to the oven and calculate the remaining cooking time according to the original weight of the joint: roast for 15-20 minutes per 500g for medium-rare (55°C) or 20-25 minutes per 500g for medium (60°C). Use a cook’s thermometer if you have one. Baste both the joint and the potatoes every now and again as they cook.

Meanwhile, combine all the chimichurri ingredients in a bowl. Stir in 1 tbsp water and set aside to allow the flavours to mingle.

Once the beef joint is cooked to your liking, transfer it to a board, cover loosely with foil and leave to rest. At the same time, increase the oven temperature to 220°C, gas mark 7. Baste the potatoes, then return them to the oven for 5-10 minutes to crisp up. Carve the beef and serve with the hasselback potatoes, the chimichurri spooned over and some steamed greens on the side, if liked.