To cook, set the oven 200°C (400°F) Gas Mark 6.
Make about 10 incisions in the lamb with a sharp knife. Push a sliver of garlic and a sprig of rosemary into each hole. Place the lamb in a roasting tray with some chopped onions and a head of garlic cut in half. Mix together the crushed garlic, orange rind, honey and olive oil. Spread the mixture over the lamb. Place in the oven and roast for 30 minutes. Then add the glass of wine and a glass of water, this will stop the honey from burning. Reduce the oven temperature to 180°C (350°F) Gas Mark 4 and continue the cooking for another hour for pink lamb. Rest for 15 minutes before serving.
When the lamb is cooked remove from the roasting tray and strain the juices, keep the garlic to serve with the lamb. To the juices, add another dash of wine and a tablesp. of redcurrant jelly. Boil it up to make a jus, finish with a knob of butter and taste for seasoning.
To make the dressing, gently heat the redcurrant jelly, orange juice, port and mint. Add a little lemon juice if you think it is too sweet. Serve warm with the sliced lamb.