Tempering: Remove the lamb from refrigeration 60 minutes prior to roasting to ensure even heat penetration.
Oven Calibration: Preheat the oven to 165°C (325°F) and position the rack in the lower-middle section.
Scoring: Use a sharp chef's knife to score the fat cap in a diamond pattern, approximately 5mm deep.
Glaze Preparation: In a small bowl, whisk together pomegranate molasses, minced garlic, rosemary, thyme, olive oil, salt, and black pepper.
Application: Thoroughly coat the lamb with the glaze, ensuring the mixture is pressed into the scored fat and distributed evenly across the surface.
Roasting: Place the lamb on a roasting rack in a heavy-bottomed pan. Roast until the internal temperature reaches 57°C (135°F) for medium-rare.
Resting: Transfer the roast to a carving board and tent loosely with aluminum foil. Allow the meat to rest for 20 minutes to permit juice redistribution.
Finishing: Carve the lamb against the grain into thin slices and garnish with fresh pomegranate arils.