Taken from the hind leg of the animal. This cut includes the bone, which adds to the depth of flavor during cooking. 

A versatile cut that lends itself to different cooking methods.

1. Roasting: This is the most common way to cook a bone-in leg of lamb. Roasting it with the bone in imparts additional flavor to the meat. For a more crusty exterior, you can sear the lamb on all sides at a high temperature before roasting it.
   The roast leg is usually cooked to medium-rare (about 135°F or 57°C internal temperature) or medium (140-145°F or 60-63°C).
   
2. Grilling: If you have a smaller bone-in leg or prefer to break it down into smaller cuts, grilling is a fantastic option. 
3. Braised: Braising the bone-in leg of lamb can be done in a large pot with broth, wine, or a flavorful liquid. This method results in tender, falling-off-the-bone meat, as the slow cooking process breaks down the muscle fibers.
   
4. Slow-cooking: Using a slow cooker or a Dutch oven for long cooking times is another great method. Bone-in cuts benefit greatly from slow cooking because the bone imparts additional richness to the broth or sauce.