1 Heat the oven to 325F.
2 Cut the lamb into chunks: Remove the wrapping and and trim any excess fat from the exterior of the lamb. Open up the leg so you see where the bone was removed, then follow the deep cracks running between the muscles to separate the leg into smaller pieces.
Cut each of these smaller pieces into roughly 3-inch chunks for the stew. You may have some smaller or larger pieces; that’s OK. Sprinkle the meat all over with salt and black pepper.
3 Brown the lamb: In a large heavy-bottomed pot or Dutch oven over medium-high heat, heat 2 tablespoons of the oil. Add the meat and let it cook for 3 minutes without disturbing. Don’t crowd the pan; work in batches if necessary. The meat may stick at first, but will easily lift after a few minutes. Turn and brown the other sides for 3 minutes more. Transfer the meat to a bowl.
4 While the lamb is browning, prepare the onions. Slice off any straggly roots from the onions, leaving the firm root centers intact. Cut the onions in half from tip to root. Peel off the papery outer layers of skin. Cut each half into a few wedges, slicing through the root so that the wedges stay intact.
5 Cook the onions: Heat the remaining 2 tablespoons oil in the pan and add the wedges, cut sides down, crowding them as close together as possible. Brown for 2 minutes, then turn and brown the other sides for 2 minutes more. Try to keep the wedges intact as you turn them. Transfer to the bowl with the browned meat.
6 Add the seasonings to the pan: Stir the garlic, shallots, cinnamon, cumin, coriander, cayenne, and allspice into the pan. Cook, stirring, for 1 minute. Add the tomatoes and cook 1 minute more or until the mixture is smooth. Stir in the water, scraping up any browned bits that might be stuck to the bottom of the pan.
7 Braise the lamb: Return the meat and onions to the pan and stir into the liquid. Add the bay leaf. Bring to a boil.
Cover the pan and transfer to the oven. Cook for 1 hour.
8 Add the raisins and chickpeas to the stew. Gently stir so some of the chickpeas are submerged in the liquid.
Cover and return to the oven. Continue cooking for 30 minutes, or until the lamb is very tender and easily pierced with a fork. If necessary, continue cooking for 30 minutes more until the lamb is tender.
9 Serve the lamb: Taste the cooking juices for seasoning and add more salt and pepper, if you like. Discard the bay leaf. Sprinkle the dish with cilantro just before serving.
The stew can also be cooled and refrigerated for up to 5 days, or frozen for up to 3 months. Warm over low heat or in a low oven before serving.