In a food processor, combine the onion, ginger, garlic, jalapeno, paprika, 1 tablespoon and 1 teaspoon kosher salt, black pepper, coriander, cumin, cardamom, cinnamon, allspice, and cloves and process until smooth. While the motor is running, add 1/3 cup of the olive oil and 2 tablespoons of the lemon juice and process to combine.

Place the lamb on a clean work surface, skin and fat side down. Rub half of the spice mixture over the lamb, then roll up tightly to form a cylinder shape and tie in 1 1/2-inch increments with butcher's twine. Rub the outside of the lamb with the remaining spice mixture and transfer to a plastic food storage bag just large enough to hold the lamb. Allow lamb to marinate for at least 6 hours, and up to overnight.

Preheat grill to medium-high heat.

Using paper towels, remove as much of the spice rub from the outside of the lamb, then rub the lamb on all sides 1 tablespoon of olive oil. Transfer the lamb to the grill and cook, turning every 15 minutes or so to promote even cooking. Grill until an instant-read thermometer inserted into the center of the lamb registers 145 degrees F for medium-rare, about 1 1/2 hours. Remove the lamb from the grill and allow to rest for at least 10 minutes before serving.

Heat the broth in a medium saucepan. Add 2 tablespoons of olive oil and 3/4 teaspoon salt. When the broth comes to a boil, add the couscous, stir, and cover and let sit for 5 minutes. Uncover the couscous, fluff with a fork, and add the remaining 2 tablespoons of olive oil, olives, scallions, mint, parsley, and lemon zest, and season with salt and pepper, to taste.

Cut the butcher's twine away from the lamb and slice into thin slices. Serve the couscous with lemon wedges for guests to add more lemon juice, to taste.