My mom always grills a leg of lamb for Easter, and over time I have successfully wrestled that responsibility away from her. This was done under the guise of “helping,” but selfishly I’d rather be outside grilling than setting the table or answering the door! This annual experience also taught me how to manage a larger cut of meat on the grill. (Though this can also be easily made by roasting in the oven instead.) There are a few different muscles that come together in the leg, some thick and some thin. Turning the lamb frequently during grilling helps cook it evenly. That method applies to this Xinjiang-inspired lamb shoulder here; it’s a little smaller and fattier, which makes it extra tasty. —lallimusic
Pulverize sesame seeds, peppercorns, cumin seeds, and fennel seeds in a mortar and pestle until coarsely ground (or use a spice grinder). Line a rimmed baking sheet with parchment paper. Place the lamb on the paper and season both sides with salt, then with the spice mix. Drizzle with oil and rub it evenly over. Roll the lamb into a bulky cylinder, then tuck the paper over and around the meat to cover (no need to tie it). Return it to baking sheet and refrigerate for 24 to 48 hours.
Remove the lamb from the refrigerator a couple of hours before you want to start cooking; it will cook more quickly and evenly if it’s not fridge-cold. Prepare a grill for medium direct heat: You should have a moderate, even layer of ash-colored charcoal when it’s ready. If you can hold your hand 6 inches above the grates for 10 seconds without recoiling in pain, that’s medium. Clean and oil grates. Unroll the lamb and grill, turning every 4 to 5 minutes or any time there’s a flare-up, until it is mahogany brown all over, the spices are golden and crisp, and a digital thermometer inserted into the center of multiple areas registers 140° to 145°F for medium-rare to medium, 40 to 45 minutes. (A single reading could be inaccurate.)
Let lamb rest off the heat for 20 minutes before carving it into thin slices against the grain. This is also excellent cold or at room temperature. The lamb goes beautifully with garlicky Whipped Aïoli, which can also be used as a schmear if you want to turn the lamb into a sandwich.