For the Horseradish Sauce: Put the shredded horseradish into a bowl with the vinegar, lemon juice, mustard, salt, pepper, and sugar. Fold in the softly whipped cream, but do not overmix or it will curdle. It keeps for 2-3 days, but cover it tightly so it does not pick up other flavors in the refrigerator.

An hour or so before you plan to cook the meat, score the fat lightly, brush the surface of the meat with olive oil and coat with freshly cracked black pepper.

Preheat the oven to 475°F. Place the meat in a roasting pan, fat side up, sprinkle with sea salt and put into the fully heated oven. Roast for 15 minutes, then reduce the temperature to 350°F. As the fat renders down it will baste the meat. Calculate the cooking time per lb and roast until the beef is cooked to your taste.

Make the batter for the Yorkshire pudding and leave to rest for about 1 hour. Make the horseradish sauce, cover and refrigerate.

Test the meat by pressing a lean surface: if the flesh springs back readily and feels quite soft, it is rare. Alternatively use a meat thermometer, but do not let it touch a bone, otherwise the reading will be inaccurate. (Beef is rare at an internal temperature of 140°F, medium at 158°F and well done at 167°F.)

When the meat is cooked, allow to rest on a plate in a warm oven for 15-30 minutes before carving, depending on the size of the roast. The internal temperature will continue to rise as much as 4-6°F, so remove the roast from the oven while it is still slightly less done than you would like. Increase the oven to 450°F.

Degrease the roasting pan, reserving the beef fat for roasting potatoes and cooking the Yorkshire pudding. Bake the Yorkshire puddings for 20 minutes.

Pour the beef broth into the roasting pan, put back on the heat and bring to a boil, and add a dash of red wine if you wish. Use a whisk to ensure that all the caramelized meat juices on the tin are dissolved. Season with salt and freshly ground black pepper and thicken with a small quantity of gluten-free roux if you wish. Taste and strain into a hot sauceboat.

Transfer the meat to a hot carving dish, adding any meat juices to the gravy. Cut the meat into slices about 1/2 inch thick with a sharp carving knife. Serve on hot plates with a little gravy, Yorkshire pudding, and roasted red onions. Serve the horseradish sauce separately.