REMOVE THE BONES: Turn the leg of lamb on its back and, using a sharp boning knife, make a T-shaped incision—horizontally, across the thickest end of the leg, then vertically, down its length—to expose the bones. Beginning with the hipbone, sever the joint and remove it, scraping flesh from bone as you go. Repeat to remove the leg bone and shank.
SEPARATE THE MUSCLES: Following the natural divisions of the muscle (where the fat and connective tissue run through the meat), gently pull the lobes of flesh apart. Use the knife to release the tendons and silver skin, and trim fat—leaving some fat to flavor and tenderize the meat. Divide the leg into four or five evenly sized pieces of meat.
SECURE THE BUNDLES: For cooking, roll the trimmed pieces of meat into bundles and tie with several lengths of kitchen string. Be sure that the bundles are of similar shape and size, so that the meat will cook evenly. If you have several smaller pieces, combine them to make a larger bundle.