This BBQ boneless leg of lamb is packed with flavour thanks to a bold Moroccan lamb marinade made with harissa, garlic, lemon, olive oil and warm spices. Butterflied lamb cooks much faster than a traditional leg of lamb, stays beautifully succulent and is easy to slice for serving. Grill it on the barbecue when the sun is out, or cook it in the oven if the weather changes. In partnership with Lamb – Try It Love It.
Summer means barbecue, at least in theory. Even if the forecast is not on your side, this marinated butterflied leg of lamb is a flexible recipe that works beautifully both outdoors on the grill and indoors in the oven. The meat is rich, tender and full of aromatic flavour, making it ideal for relaxed entertaining, family meals and weekend cooking.
Grilling Lamb
Lamb kebabs, burgers and chops are common barbecue favourites, but larger cuts of lamb are often overlooked. That is a shame, because the right cut can cook quickly, feed a crowd and deliver incredible flavour from the grill.
A boneless leg of lamb, also known as a butterflied leg of lamb, is one of the best choices for barbecuing. Once the bone has been removed, the meat is opened out so it lies flatter and cooks more evenly. This makes it much faster to grill than a whole bone-in leg, while still giving you plenty of juicy, tender meat to carve and serve.
The key to success is a good marinade, a hot barbecue for searing, and a cooler cooking zone so the lamb can finish gently without drying out. A digital thermometer is also very useful, especially when cooking a larger joint.
Simply the Best Lamb Marinade
This Moroccan-style lamb marinade combines harissa paste, minced garlic, olive oil, lemon zest, lemon juice and fragrant spices. Ground cumin, coriander, cinnamon, turmeric and garlic granules create a deep, warm flavour that pairs perfectly with the natural richness of lamb.
Harissa paste is especially good with lamb. It brings heat, depth and a savoury complexity that works well on the barbecue. Mixed with olive oil and lemon, it becomes a thick paste that coats the meat and helps create a delicious crust as the lamb sears.
For best results, marinate the lamb for at least 2 to 4 hours. If you have time, you can leave it overnight in the fridge. The longer marinating time gives the spices more opportunity to flavour the meat.
How to Barbecue Butterflied Leg of Lamb
To cook BBQ boneless leg of lamb properly, use the two-zone cooking method, also known as banked grilling. This gives you one very hot area for searing and one cooler area for indirect cooking.
If you are using a charcoal barbecue, pile the coals on one side and leave the other side empty or only lightly covered with coals. The lamb is first seared directly over the hot coals, then moved to the cooler side to finish cooking more gently.
If you are using a gas barbecue, heat it on high for the searing stage, then lower the temperature to around 150-180°C / 300-350°F for indirect cooking. This helps the lamb cook through without burning the outside.
Grilling Times and Temperatures for Lamb
The most reliable way to check whether your lamb is cooked is to use a digital meat thermometer. Insert it into the thickest part of the meat for an accurate reading. This prevents overcooking and helps keep the lamb juicy.
Cooking time will depend on the size and thickness of the lamb. A smaller butterflied leg of lamb weighing around 900g / 2 pounds may take 20-30 minutes over indirect heat after searing. A larger joint of around 2.5kg / 6 pounds may need 35-45 minutes after searing.
For medium rare lamb, aim for an internal temperature of around 62-63°C / 145°F. For medium, aim for 71°C / 160°F. For well done, aim for 76°C / 170°F. Always rest the lamb before carving so the juices can settle back into the meat.
BBQ Boneless Leg of Lamb Step by Step
STEP 1. Prepare the marinade. Add the ground cinnamon, cumin, coriander, turmeric and garlic granules to a large container. Stir in the harissa paste, minced garlic, lemon zest, lemon juice and olive oil to create a thick, fragrant paste.
STEP 2. Add the butterflied lamb and rub the marinade all over the meat. Cover and refrigerate for 2-4 hours, or overnight if preferred.
STEP 3. Prepare your barbecue for two-zone cooking. If using charcoal, pile the coals on one side and leave the other side clear or sparsely covered. Wait until the coals have turned ashy and the flames have died down before you begin grilling.
STEP 4. Remove the lamb from the fridge and let it come to room temperature for at least 30 minutes while the barbecue heats. Lift the lamb out of the marinade and discard any leftover marinade. Season both sides generously with sea salt.
STEP 5. Place the lamb fat side down on the hot side of the barbecue and sear for 4 minutes. Keep a spray bottle of water nearby in case fat dripping onto the coals causes flare-ups.
STEP 6. Turn the lamb over and sear the other side for another 4 minutes.
STEP 7. Move the lamb to the cooler side of the barbecue, fat side down. Close the lid and cook for 20 minutes, then check the temperature with a meat thermometer. The lamb is ready for medium rare when it reaches around 62-63°C / 145°F in the thickest part. If it needs more time, continue cooking for another 5-10 minutes. Larger pieces may need 35-40 minutes after searing.
STEP 8. Transfer the cooked lamb to a warm platter and cover loosely with foil. Rest for 15 minutes before slicing into thin pieces. Pour any resting juices over the sliced lamb and serve immediately.
Oven Cooking Instructions
STEP 1. Preheat the oven to 180°C / 350°F.
STEP 2. Brush a griddle pan with oil and heat until hot. Sear the lamb for 4 minutes per side, pressing down so it browns evenly. This can be smoky, so open a window or use an extractor fan.
STEP 3. Transfer the lamb to a rack set over a roasting tin. Cook for 30 minutes, then check the internal temperature. Continue cooking for another 10 minutes or longer, depending on the size and thickness of the meat. Rest before slicing and serving.
Tips for the Best BBQ Lamb
- Marinate the lamb for 2-4 hours in a covered container or large freezer bag. You can marinate it overnight if you prefer.
- Bring the meat to room temperature for at least 30 minutes before grilling. Cold meat will take longer to cook evenly.
- Use a meat thermometer for the most accurate results. Check the thickest part of the lamb.
- Rest the lamb before carving. This step is essential for juicy, tender slices.
- Make sure the barbecue is hot before cooking, but wait until the coals are ashy and any flames have settled.
- Keep a spray bottle of water nearby to control flare-ups caused by dripping fat.
What to Serve with Grilled Lamb
Serve sliced BBQ boneless leg of lamb with a simple salad, lemon wedges and your favourite side dishes. It works especially well with rice dishes, potato salad, tabbouleh, pasta salad or fresh Mediterranean-style sides.
- Dill rice with broad beans and tzatziki
- Greek spinach rice
- Greek potato salad
- Lebanese tabbouleh
- Greek pasta salad
Marinated BBQ Boneless Leg of Lamb
The marinade is enough for two boneless legs of lamb, around 900g / 2 pounds each, or one larger piece. A larger piece will require a longer cooking time.
Equipment
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Digital thermometer
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Barbecue or oven
Ingredients
Lamb Marinade
- 6 tbsp olive oil
- 4 tbsp harissa paste
- 4 garlic cloves, minced
- 1 lemon, zest and juice
- 3 tsp ground coriander
- 3 tsp ground cumin
- 2 tsp ground cinnamon
- 1 tsp ground turmeric
- 1 tsp garlic granules
For the Lamb
- 2 boneless legs of lamb, butterflied, about 900g / 2 pounds each
- Sea salt, to season
- Lemon wedges, to serve
Instructions
BBQ Boneless Leg of Lamb
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Mix the marinade ingredients in a large container to form a thick paste. Add the lamb and rub the marinade all over the meat. Cover and chill for 2-4 hours, or overnight.
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Prepare the barbecue for two-zone cooking, with a hot side for searing and a cooler side for indirect cooking.
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Remove the lamb from the fridge at least 30 minutes before cooking. Discard leftover marinade and season the lamb generously with sea salt.
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Place the lamb fat side down on the hot side of the barbecue and sear for 4 minutes.
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Turn the lamb over and sear the other side for 4 minutes.
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Move the lamb to the cooler side of the barbecue, close the lid and cook for 20 minutes. Check the internal temperature. For medium rare, aim for around 62-63°C / 145°F in the thickest part. Continue cooking if needed.
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Rest the cooked lamb loosely covered with foil for 15 minutes. Slice thinly, spoon over the resting juices and serve with lemon wedges.
Oven Cooking Instructions
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Preheat the oven to 180°C / 350°F.
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Brush a griddle pan with oil and sear the lamb for 4 minutes per side, pressing down so it browns evenly.
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Transfer the lamb to a rack set over a roasting tin. Cook for 30 minutes, then check the temperature. Continue cooking for another 10 minutes or longer depending on size. Rest before serving.
Notes
Grilling Times and Temperatures for Lamb
- Use a digital thermometer to avoid overcooking the lamb.
- Cooking times vary depending on the size and thickness of the meat. A 900g / 2 pound piece may need 20-30 minutes after searing, while a larger joint may need 35-45 minutes.
- Recommended internal temperatures: 62-63°C / 145°F for medium rare, 71°C / 160°F for medium, and 76°C / 170°F for well done.
Two-Zone Cooking Technique
- For charcoal grilling, pile the coals on one side and leave the other side clear or lightly covered.
- For gas grilling, sear over high heat first, then reduce the heat to 150-180°C / 300-350°F for indirect cooking.
Nutrition
Nutritional information is approximate and will depend on ingredient quality and serving size.