This recipe is taken directly from Weber’s official recipe library — the Moroccan-Spiced Leg of Lamb with Herb Butter recipe published on weber.com. It calls for a boneless, butterflied leg of lamb, which lays flat on the grate rather than needing the longer indirect roast a bone-in leg requires, and pairs a warm-spiced marinade with a simple herb butter finish. Safe internal temperature guidance below comes from the USDA Food Safety and Inspection Service.
Ingredients
For the herb butter
- ½ cup (1 stick) unsalted butter, softened
- 1 tablespoon finely chopped fresh Italian parsley leaves
- 2 teaspoons finely chopped fresh mint leaves
- 2 large garlic cloves, minced
- ½ teaspoon kosher salt
- ¼ teaspoon freshly ground black pepper
For the marinade
- ⅔ cup extra-virgin olive oil
- ½ cup finely chopped fresh Italian parsley leaves and tender stems
- ⅓ cup fresh lemon juice
- 1½ tablespoons kosher salt
- 1½ tablespoons paprika
- 2 teaspoons ground cardamom
- 4 garlic cloves, finely chopped
- 1½ teaspoons ground cumin
- 1½ teaspoons ground ginger
- 1½ teaspoons ground turmeric
For the lamb
- 1 boneless leg of lamb, about 5 pounds, butterflied and trimmed of excess fat
Method
- Combine the herb butter ingredients in a small bowl and set aside.
- Whisk together the marinade ingredients. Reserve and set aside half of the marinade for basting the lamb on the grill. Pour the remaining marinade into a large, resealable plastic bag, add the lamb, press out the air, and seal tightly. Turn the bag to distribute the marinade, place in a bowl, and refrigerate for 2 to 4 hours, turning occasionally.
- Remove the lamb from the bag and discard the used marinade. Let the lamb stand at room temperature for 15 to 30 minutes before grilling.
- Prepare the grill for indirect cooking over medium heat, 350° to 450°F.
- Grill the lamb, fat side down, over direct heat with the lid closed until nicely marked, 10 to 12 minutes. Turn it over and grill 5 minutes more, basting with the reserved marinade. Move the lamb to indirect medium heat and grill, fat side up, lid closed, basting occasionally, until an instant-read thermometer inserted into the thickest part registers 125° to 130°F for medium rare — Weber’s recipe puts this at another 20 to 30 minutes.
- Remove from the grill and let rest 5 to 10 minutes.
- Cut the lamb across the grain into thin slices. Melt the herb butter in a small saucepan over low heat on the stove and drizzle it over the sliced lamb before serving.
A Temperature Gap Worth Knowing
Weber’s recipe pulls the lamb at 125° to 130°F for medium rare, which sits below the USDA’s minimum. The USDA Food Safety and Inspection Service’s Safe Minimum Internal Temperature Chart lists whole cuts of lamb — steaks, chops and roasts, which a butterflied leg falls under — at a minimum internal temperature of 145°F (62.8°C), followed by a rest of at least 3 minutes. Both numbers are worth having in front of you before deciding where to pull the lamb: Weber’s medium-rare target is a doneness preference, and 145°F with a rest is the food-safety floor the USDA sets for whole cuts of lamb, distinct from the higher 160°F required for ground lamb.
A Few Practical Notes
Butterflying a boneless leg opens it into an irregular, unevenly thick piece of meat rather than a uniform roast, which is exactly why this method starts it fat side down over direct heat to mark and partially render the fat, then finishes it fat side up over indirect heat rather than direct heat the whole way through — the thicker sections get more time near the heat without the thinner sections drying out or the exterior burning before the center catches up. Basting with the reserved half of the marinade during both the direct and indirect stages keeps the surface from drying out over the longer indirect cook. As with the herb butter, warming it gently in a saucepan rather than microwaving it keeps it from separating before it’s drizzled over the rested, sliced lamb.
The marinade itself does double duty in this recipe: it flavors the lamb during its 2-to-4-hour refrigerated soak, and the reserved half becomes a basting liquid once the lamb is actually on the grill, rather than being discarded after marinating like the used portion is. That’s a meaningfully different approach from recipes that treat marinating and basting as separate liquids — here the same spice blend of paprika, cardamom, cumin, ginger and turmeric carries through both stages of cooking. Letting the lamb come back to room temperature for 15 to 30 minutes before it goes on the grill, rather than starting it cold from the refrigerator, is also part of why the direct-heat marking stage only needs 10 to 12 minutes to take on color.
Because the recipe calls for indirect medium heat at 350° to 450°F for the second stage rather than a fixed single number, actual grill setup matters more here than in a direct-heat-only recipe — a kettle grill with coals banked to one side, or a gas grill with one or more burners turned off, both qualify as “indirect,” but the 20-to-30-minute window Weber gives for reaching 125° to 130°F assumes the indirect zone is actually within that 350°–450°F range rather than running hotter or cooler.
Keep reading
- Grilled Lamb Loin Chops with Fennel Herb Salad
- Weber’s Grilled Swordfish with Jalapeño-Mint Butter
- Lemon-Rosemary Grilled Chicken and Marinade Safety
- Weber’s Harissa Chicken Thighs on the Grill