Place the lamb in a dish. Puree the remaining
ingredients then pour them over the lamb, cover and
refrigerate overnight, turning and basting
occasionally.
Roast the lamb in a preheated oven at
220C/425F/gas mark 7 for 10 minutes then reduce
the heat to 190C/375F/gas mark 5 and continue to
cook for 20 minutes per 450 g/1 lb plus 20 minutes,
basting occasionally with the marinade.