Grilled Butterflied Leg of Lamb

This leg of lamb is butterflied for easy grilling and marinated with rosemary and garlic to give it great flavor. Make it for a big summer cook-out, or for a twist on Easter dinner.

By
Elise Bauer
Elise Bauer
Elise Bauer
Elise founded Simply Recipes in 2003 and led the site until 2019. She has an MA in Food Research from Stanford University.
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Updated March 14, 2023
Elise Bauer
Grilled Butterflied Leg of Lamb sliced on a cutting board

Simply Recipes / Elise Bauer

Where to start? Somehow I suspect that the following method—fat is good, flame is good—is going to get me in trouble with some of you. But since this was the best lamb roast I've ever eaten in my life, I will forge ahead and tell you how we did it.

The lamb roast was succulent—crusty, flavorful char on the outside, pink and tender on the inside.

Tips for Grilling Leg of Lamb

Note that the more fat on the lamb roast, the more likely you'll have flare-ups when you grill. Flare-ups are okay as long as they are controlled and don't get out of hand.

To make it easier to turn on the grill, I recommend inserting a few metal skewers through the lamb, crosswise and parallel to the surface of the lamb.

Marinate Before Grilling

By the way, it used to be that people were worried about char grilling being carcinogenic. Turns out if you marinate the meat in an acid-based marinade first, you help negate the cancer-causing elements. (Grillers everywhere rejoice.)

The marinade I'm using for this recipe is made with onion, garlic, rosemary, lemon zest, apple cider vinegar, and olive oil. Purée it all in a food processor and let the lamb marinate in it for one to two hours before grilling.

Grilled and Marinated Leg of Lamb sliced on a board

Simply Recipes / Elise Bauer

Butterflying Leg of Lamb

Why use a butterflied leg of lamb? A butterflied lamb roast is one that has the leg bone removed so that you can lay the roast out flat. You can do it yourself or have your butcher do it. Laying the roast flat on the grill helps it cook faster and more evenly.

What to Serve With Grilled Lamb

Some people take offense at the very idea of using mint jelly with lamb. I wouldn't have lamb without it. Homemade mint jelly is fantastic with lamb. And if we're out, I've been known to chop up some fresh mint leaves just to go with the lamb. So, to each her own when it comes to the jelly. (Mint chimichurri or Horseradish sauce are also good!)

For side dishes, try braised leeks, a fresh arugula salad, or grilled asparagus.

Love Lamb? Try These Recipes!

Grilled Butterflied Leg of Lamb

Prep Time 20 mins
Cook Time 45 mins
Marinate and Rest: 2 hrs
Total Time 3 hrs 5 mins
Servings 8 to 10 servings

In this recipe, we sear the lamb first on both sides by grilling on high heat for a short amount of time. Then we cook the lamb on lower heat until it is cooked through. In our opinion, the only way to eat lamb is medium rare or rare.

There is nothing more depressing than dried-out, over-cooked lamb. For this reason, it is essential that you use a meat thermometer to test the internal temperature of the roast.

Ingredients

  • 1/2 onion

  • 4 cloves garlic, peeled

  • 2 tablespoons fresh rosemary leaves, or 1 tablespoon dried

  • Zest of 1 lemon

  • 1 tablespoon apple cider vinegar

  • 2 tablespoons extra virgin olive oil

  • Kosher salt and freshly ground black pepper

  • 1 boneless leg of lamb, 5 to 6 pounds, butterflied

Method

  1. Make the marinade:

    Put onion, garlic, rosemary, lemon zest, apple cider vinegar, and olive oil into a food processor and pulse to combine. (If you don't have a food processor, just chop the onions, garlic, and rosemary very well and combine with the rest.)

  2. Marinate the lamb:

    Sprinkle a generous amount of salt and pepper over the lamb. Place marinade and lamb into a 1-gallon freezer bag. Spread marinade over all sides of the meat. Seal the bag and refrigerate for 1 to 2 hours.

    lamb marinade in ziploc bag
    Elise Bauer
  3. Bring lamb to room temperature:

    Remove lamb from refrigerator and let come to room temperature (about 30 minutes). When ready to put on grill, remove from marinade bag.

    To help make the lamb easier to turn on the grill, you can insert a couple of skewers through the lamb, crosswise. (A tip learned from Rick Rodgers in Kingsford Complete Grilling Cookbook.)

    marinated leg of lamb in dish
    Elise Bauer
  4. Prepare the grill:

    If you are using a charcoal grill, prepare the coals so that they are double-layered on one side of the grill, and sparsely single-layered on the other side of the grill (this is called "banked" grilling).

    If you are using a gas grill, heat the grill on high on all burners to start. After the initial browning, you will reduce the heat.

  5. Sear the lamb:

    Place the lamb, fat side down, on the grill on the hot side (double-layer charcoals). You will get likely get flare-ups, so be prepared with a squirt bottle of water or a couple of cups of water (if using a charcoal grill) to control the flames if needed. (My brother Matt swears by shaking the bottle of beer he is drinking to squirt some beer on the coals when needed for flareups.)

    Sear one side for 4 minutes, then flip the lamb over to sear the other side for another 4 minutes.

    marinated butterflied leg of lamb on grill
    Elise Bauer
    butterflied leg of lamb on grill with thermometer in it
    Elise Bauer
  6. Move to cool side of grill and finish cooking:

    If you are using a charcoal grill, move the roast to the less hot side of the grill. If you are using a gas grill, lower the heat to low. You will want to maintain a temperature of 300-350°F.

    Cover the grill and let cook for an additional 35 to 45 minutes (depending on how thick, and how many pounds the roast is), until a meat thermometer inserted into the thickest part of the roast registers 120°F for rare or 130°F for medium rare.

  7. Let rest before cutting:

    Transfer to a cutting board with a well to catch the juices. Cover with aluminum foil and let rest for 5 to 10 minutes. Remove the skewers if you are using any.

    Cut across the grain, 1/4 to 1/2-inch thick slices. Serve slices on a warm platter; pour meat juices over the slices. Serve with mint jelly or horseradish.

Nutrition Facts (per serving)
614 Calories
40g Fat
1g Carbs
58g Protein
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Nutrition Facts
Servings: 8 to 10
Amount per serving
Calories 614
% Daily Value*
Total Fat 40g 51%
Saturated Fat 16g 80%
Cholesterol 211mg 70%
Sodium 180mg 8%
Total Carbohydrate 1g 0%
Dietary Fiber 0g 1%
Total Sugars 0g
Protein 58g
Vitamin C 1mg 5%
Calcium 30mg 2%
Iron 5mg 25%
Potassium 727mg 15%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
Nutrition information is calculated using an ingredient database and should be considered an estimate. In cases where multiple ingredient alternatives are given, the first listed is calculated for nutrition. Garnishes and optional ingredients are not included.