Mediterranean Rotisserie Leg of Lamb with Potatoes, Fennel, and Olives

1. 1Combine the garlic, zest, oil, and 2 teaspoons of the salt in a small bowl and set aside. Combine the remaining 2 teaspoons of salt, paprika, coriander, and cumin in a separate small bowl and set aside.
2. 2Have 7 or 8 (20-inch) lengths of butcher’s twine ready. Remove and discard any mesh netting or string around the lamb. Unroll the lamb and lay it flat and fat-side down on a work surface. Using your hands, rub all of the lemon-garlic mixture evenly over the surface of the lamb and season with pepper. Roll the lamb back into a tight cylinder and tie it crosswise with the twine pieces, spacing them about 1 1/2 inches apart. Trim off any excess twine. Using your hands, rub all of the spice mixture evenly over the outside of the lamb; set aside.

To cook the lamb and vegetables:

1. 1Remove the rotisserie center rod (spit) and fork prongs from an outdoor gas grill with a rotisserie attachment. Turn on the rotisserie burner, turn on the left and right grill burners to medium (leave the middle burner off), and let the grill heat to medium (about 350°F to 450°F). Meanwhile, load the lamb onto the spit and prepare the vegetables.
2. 2Slide 1 pronged fork onto the spit with the tines facing inward, setting it about 10 inches from the end of the spit, and tighten the fork halfway. Slide the spit through the center of the lamb lengthwise and push the lamb onto the fork tines until it’s firmly embedded. Attach the other pronged fork with the tines facing inward and slide it down until it’s firmly embedded in the lamb. If necessary, adjust the forks and lamb so that they are centered on the spit. Tighten both forks into place; set aside.
3. 3Line a rimmed baking sheet with aluminum foil. Cut the potatoes in half and place them on the baking sheet. Add the fennel and onion, drizzle with the oil, add the measured salt, and season with pepper; toss with your hands to combine. Turn all of the potato pieces cut-side down. Sprinkle in the olives; set aside.
4. 4When the grill is ready, load the pointed end of the spit onto the rotisserie motor. Place the sheet of vegetables directly on the grill grates underneath the lamb. Turn on the rotisserie motor, cover the grill, and cook, stirring the vegetables every 30 minutes, until an instant-read thermometer inserted into the center of the lamb registers 135°F to 140°F, about 1 to 1 1/2 hours.
5. 5Turn off the rotisserie motor, rotisserie burner, and grill burners. Using potholders or kitchen towels, carefully remove the spit to a cutting board and loosen the forks. Remove the lamb from the spit and remove the forks. Tent the lamb loosely with aluminum foil and let it rest for at least 10 minutes. Remove the tray of vegetables from the grill and cover with aluminum foil.
6. 6Cut and discard the twine from the lamb. Cut the meat crosswise into 1/2-inch-thick slices and serve with the vegetables.