Step 1: Prepare the marinade

• In a small bowl, combine minced garlic, rosemary, thyme, oregano, black pepper, salt, coriander, cumin, lemon zest, lemon juice, olive oil, and mustard

• Mix into a thick, fragrant paste

Step 2: Season the lamb

• Lay the lamb flat, fat side down

• Rub half the marinade inside the meat, then roll and tie it securely with butcher’s twine

• Rub the remaining marinade all over the outside of the lamb

• Place in a dish, cover, and refrigerate for 4–12 hours to marinate

Step 3: Bring to room temperature

• Remove the lamb from the fridge about 1 hour before cooking

• Let it rest at room temperature to ensure even cooking

Step 4: Prepare the roasting pan

• Preheat oven to 300°F (150°C)

• Scatter sliced onions, carrots, and celery in the bottom of a roasting pan

• Add water or broth to the pan

• Place a roasting rack over the vegetables and set the lamb on top

• Drizzle with a little olive oil

Step 5: Slow roast the lamb

• Roast uncovered for about 3–3½ hours or until internal temperature reaches 145°F (63°C) for medium doneness

• Baste the lamb once or twice with pan juices during cooking

• For a more browned crust, increase the oven temperature to 425°F (220°C) for the last 15 minutes of roasting

Step 6: Rest and slice

• Transfer the lamb to a cutting board and tent loosely with foil

• Let it rest for 20–30 minutes before slicing

• Strain pan drippings and serve as a jus or reduction sauce if desired