Remove the lamb from the refrigerator 2 hours before you intend to roast it. Strip off the skin that covers the fat. Season the fat with salt and freshly ground black pepper, then leave the meat to stand at room temperature until it has lost its chill. Heat the oven to 200°C /400°F /gas 6.

Heat a frying-pan, lay the lamb in it, fat side down, and sear over a high heat until the fat takes on a little colour.

Spread 25 g (l oz) of the softened butter over the best ends. Stand them up in a roasting tin, cover the rib bones with foil, and roast in the oven for 20 minutes. Remove the tin from the oven and leave the meat aside while you prepare the topping. Do not switch off the oven.

Prepare the topping: mix together the breadcrumbs, Parmesan cheese and dried herbs, then add the grated lemon zest, beaten egg and the rest of the softened butter and make a paste. Use half of this mixture to coat the fatty side 6" each best end. Return the best ends to the oven, again covering the rib bones with foil, and roast for a further 30 minutes for pink meat, or 40 minutes for well done. Baste the lamb occasionally towards the end of the cooking time with the fatty juices. Meanwhile, heat the grill to moderate.

When the lamb is cooked, transfer it to a well-heated serving platter. Leave to settle in a warm place for 10 - 15 minutes. While it settles, grill the tomatoes. Transfer the tomatoes to the serving platter, garnish with sprigs of watercress and serve. Carve down between the bones and serve each person 2 cutlets.

• For an alternative topping omit the oregano and the Parmesan cheese and replace these with finely chopped parsley.