Preheat the oven to 350 degrees F.

  Place the cranberries, cranberry jelly, wine, stock, vinegar and sugar in a saucepan and simmer until the mixture has reduced by one-third.

  Place the onions in a roasting pan big enough to fit the lamb comfortably.  The roasting pan shouldn't be too big as you don't want all the sauce evaporating too quickly.  Don't forget that the lamb will shrink while cooking.

  Place the sprigs of rosemary on top of the onions and lay the lamb, boney side facing you, on top.

  Grind coarse black pepper over the lamb and tuck the garlic and mint into all its cracks and crevices.

  Pour over the reduced sauce and sprinkle with coarse salt.

  Roast uncovered for about 1 hour.  Baste every now and then with the sauce.

  Reduce the heat to 330 F, turn the meat, and continue to roast, uncovered, for a further 45-60 minutes until golden brown.  Then cover the meat with foil and roast for a further hour.

  Keep warm on a low heat until ready to serve.

  Enjoy with potatoes, butternut and minted peas or a crisp green salad with fresh cranberries.