Roast beef with mushroom & sherry sauce

Preheat the oven to 220°C, gas mark 7. Put the beef fat-side up in a roasting tin, rub it with 1 tbsp oil on all sides except the top (where the fat is), then season if liked. Roast for 15 minutes. Meanwhile, boil the potatoes in a large pan of boiling salted water for 8-10 minutes until almost tender. Drain in a colander; allow to steam-dry for 1 minute. Put the potatoes in a second, large roasting tin, drizzle with 3 tbsp oil and toss to coat and rough up the edges. Add the carrots to the potato tin (halve any larger ones lengthways), turn them in the oil and season.

Turn the oven temperature down to 180°C, gas mark 4, put the second roasting tin on the shelf under the beef and roast for 25-30 minutes. Check the beef with a meat thermometer: it should read 50ºC for rare or 60ºC for medium. Once the beef is cooked to your liking, remove it from the roasting tin, wrap tightly in foil and allow to rest on a plate while the carrots and potatoes finish cooking.

While the beef is resting, increase the oven temperature to 200°C, gas mark 6. Pour the juices from the beef tin over the carrots and potatoes. Roast, turning once or twice, for 35-40 minutes more, until the potatoes are golden and crisp and the carrots are caramelised.

Meanwhile, make the sauce. Soak the wild mushrooms in a bowl of warm water for 20 minutes, then drain, pat dry and roughly chop. Heat the oil in a large frying pan over a high heat and fry the chestnut mushrooms for 8-10 minutes, turning occasionally, until golden and tender. Season, then put on a plate and set aside.

Put the frying pan back on a medium heat and melt the butter, then fry the shallot and chopped wild mushrooms for 5-6 minutes until softened but not taking on colour. Stir in the flour and crushed garlic; cook for 2 minutes more, stirring frequently, then increase the heat, add the sherry and bubble for 2 minutes until almost evaporated. Gradually stir in the stock, add the whole rosemary sprigs, then bring to a simmer and cook for 6 minutes, until thickened enough to lightly coat the back of a spoon.

Add the chestnut mushrooms back to the frying pan with the double cream and simmer for 1 minute more, then carefully remove and discard the whole rosemary sprigs. Season and add the sherry vinegar. Stir through the chopped rosemary, then keep warm. Unwrap the beef and carve into thin slices, then serve with the potatoes, carrots and your favourite green vegetables, spooning over the sauce.