Take the lamb out of the refrigerator at least 1 hour before cooking to bring it to room temperature. Pat it dry with paper towels and trim any excess fat if necessary, leaving a thin layer.

In a small bowl, mix the minced garlic, chopped rosemary, olive oil, lemon zest, salt, and pepper to form a thick paste.

Use a sharp knife to make shallow cuts in a crisscross pattern across the fat cap of the lamb.

Generously massage the garlic and rosemary mixture all over the lamb, ensuring it gets into the scored areas. Let the lamb sit for 30 minutes to absorb the flavors.

Preheat your oven to 375°F (190°C). Place the lamb on a roasting rack in a pan. If using vegetables, scatter them around the bottom of the pan.

Roast the lamb for about 1 hour and 45 minutes, or until the internal temperature reaches 135°F (57°C) for medium-rare. Use a meat thermometer for accuracy.

Remove the lamb from the oven and tent it loosely with aluminum foil. Let it rest for 15–20 minutes before carving.

Carve thin slices against the grain using a sharp knife. Serve with roasted vegetables and pan drippings.