Place the meat in a roasting tin and, using a small sharp knife, make about 6-8 evenly spaced incisions into it. Into these slits push slivers of garlic and the coriander seeds (crushed a bit first, using either a pestle and mortar or the back of a tablespoon). Add a knob of dripping to the roasting tin and roast for 30 minutes to the pound (450 g), basting with the juices from time to time. When the lamb is cooked, carve it into thick slices and keep warm. Then strain off the fat from the roasting tin and add a little stock or dry cider to the juices to make a gravy. Redcurrant jelly is a nice accompaniment.