Porcini-buttered roast beef sirloin with pickled peppercorn sauce

Method

• step 1

  The night before, prepare the peppercorns for the sauce. Put the green peppercorns and vinegar in a small bowl, cover and leave at room temperature overnight.

• step 2

  The next day, pat the beef dry with kitchen paper, cover loosely, and leave for 1 hr at room temperature – this helps to ensure perfectly cooked meat later. Put the dried porcini mushrooms and black peppercorns in a small blender or spice grinder, and blitz to a powder. Mash with the butter and set aside.

• step 3

  Heat the oven to 230C/210C fan/gas 8. Season the sirloin all over with the sea salt. Heat the oil in a flameproof roasting tin or large frying pan over a high heat, and sear the beef, fat-side down, for 5-8 mins until some of the fat has rendered out and turned golden brown, then holding the beef with tongs, sear it on all sides for 2-3 mins until browned all over. Sit the browned beef in the roasting tin fat-side up and spoon out most of the fat (if you have rendered it in the tin). Spoon 2 tbsp of the rendered fat over the beef and reserve any leftover fat for making yorkshires. Arrange the shallots around the beef, turning to coat them in the fat.

• step 4

  Roast for 20 mins, then dot the porcini butter all over the beef and reduce the heat to 180C/160C fan/gas 4. Roast for another 40-50 mins for rare to medium-rare, or 1 hr for medium-well. If you have a meat thermometer, it should read 55C for medium-rare, or 65C for well done. Baste the meat in the butter from the tin, then transfer to a warm platter or board with the shallots. Cover and leave to rest for 20 mins.

• step 5

  To make the sauce, discard all but 4 tbsp fat from the tin and set the tin over a low heat (or transfer to a pan), and fry the chopped shallots for 6-8 mins until softened and translucent. Strain the pickled peppercorns, reserving the vinegar, and add to the pan along with the stock. Bring to a simmer and cook for 10 mins until reduced by about half, then whisk in the cream. Taste for seasoning, and add the reserved vinegar, 1 tsp at a time, to balance the acidity and creaminess (we used about 5 tsp). Simmer for another 5-6 mins until the sauce has thickened. Pour into a jug. Carve the beef and serve with the roasted shallots and sauce.