How to Make It
Preheat the oven to 250°. In a small bowl, combine the garlic with the thyme, cumin seeds, rosemary, curry, salt, ground cumin and coriander, coriander seeds and white pepper. Cut 16 slits, each about 1 inch long by 1 inch deep and spaced 1 inch apart, in the meat. Rub the spice mixture all over the lamb, working it into the slits. Set aside any spice mixture that does not adhere.
In a medium flameproof casserole, heat the oil. Add the lamb and lightly brown it on all sides over moderate heat, about 2 minutes per side. Add the stock and any remaining spice mixture. Cover with a sheet of buttered wax paper and a lid. Braise the lamb in the oven for 3 hours, or until very tender. Check the meat from time to time and baste as necessary to prevent it from drying out.
Transfer the lamb to a carving board. Strain the cooking juices through a fine sieve; skim the fat. Transfer the juices to a gravy boat. Thickly slice the lamb and serve with the juices.