Roasted Butterflied Leg of Lamb

Written by
Linda Larsen
Linda Larsen is a journalist, quick-cooking and slow-cooking expert, and accomplished cookbook author with over 30 years of experience in testing and developing recipes.
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Linda Larsen
Updated 04/13/21
Roasted Butterflied Leg of Lamb

The Spruce
Prep: 15 mins
Cook: 60 mins
Marinate Time: 24 hrs
Total: 25 hrs 15 mins
Servings: 10 to 12 servings
Nutritional Guidelines (per serving)
536 Calories
36g Fat
1g Carbs
49g Protein
See Full Nutritional Guidelines Hide Full Nutritional Guidelines
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Nutrition Facts
Servings: 10 to 12
Amount per serving
Calories 536
% Daily Value*
Total Fat 36g 46%
Saturated Fat 14g 68%
Cholesterol 176mg 59%
Sodium 403mg 18%
Total Carbohydrate 1g 1%
Dietary Fiber 0g 1%
Total Sugars 0g
Protein 49g
Vitamin C 2mg 10%
Calcium 28mg 2%
Iron 4mg 22%
Potassium 620mg 13%
*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.)

A leg of lamb is always a great cut to serve for a special meal. While it's usually cooked bone-in, a boneless leg of lamb is easier and faster to cook and equally succulent and juicy. By asking your butcher to "butterfly" the leg, the resulting cut is a boneless piece of lamb that can be cooked flat or rolled up. Sweet and gamey, our recipe brings you beautifully cooked, tender lamb with a crusty and delicious outer layer.

Some recipes for a butterflied leg of lamb secure the meat with long skewers or kitchen twine, but we found that cooking the meat as-is also produces a lovely result without the extra work. If you decide to secure the meat, run 2 long metal skewers lengthwise and 2 crosswise, or roll and tie the meat at 1 1/2 inch intervals. This recipe makes spectacular leftovers for sandwiches, salads, shepherd's pie, or stuffed pitas.

A fragrant marinade of mustard, herbs, and garlic flavors the meat. The result is a tender lamb that you can pair with side dishes of your choice. We recommend simple accompaniments like roasted potatoes, grilled asparagus, and mint sauce. It is up to you to add other ingredients to the roasting pan: sliced carrots, potatoes, zucchini, leeks, peppers, and eggplants can add to the flavor of the meat and be your side dish. Simply drizzle olive oil on the vegetables of your choice and season with salt and pepper.

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Ingredients

  • 1 small onion, chopped

  • 3 cloves garlic, minced

  • 1/4 cup olive oil

  • 1/4 cup red wine vinegar

  • 3 tablespoons Dijon mustard

  • 2 tablespoons orange juice

  • 2 teaspoons fresh thyme leaves, minced

  • 2 teaspoons fresh rosemary leaves, minced

  • 1 (4- to 5-pound) boneless leg of lamb, butterflied

  • 1 teaspoon salt

  • Freshly ground black pepper, to taste

Steps to Make It

  1. Gather the ingredients.

    Ingredients for roasted lamb
    The Spruce 

  2. In a heavy-duty zipper storage bag, combine the onion, garlic, olive oil, vinegar, mustard, orange juice, thyme, and rosemary and mix well.

    Ingredients combined in zip-top bag
    The Spruce

  3. Place the leg of lamb in the marinade, seal the bag, and turn to coat. Massage the meat through the bag for a bit to help the marinade penetrate and coat all the meat evenly. Put the storage bag into a large roasting pan and marinate for 24 hours in the refrigerator.

    Meat marinating in a bag
    The Spruce

  4. Preheat the oven to 350 F. Remove the lamb from the marinade and place it in a shallow roasting pan. Season with salt and pepper.

    Lamb in metal baking pan seasoned with salt and pepper
    The Spruce

  5. Roast the lamb, uncovered, for 50 to 70 minutes, basting it with the marinade several times during the process. Cook until an instant-read meat thermometer registers 145 F (for medium-rare) or 150 F (for medium) when inserted in the thickest part of the meat. For safety reasons, the lamb needs to be cooked to a minimum of 145 F.

    Lamb roasting in a pan
    The Spruce

  6. Remove the lamb from the oven, cover with foil, and let stand for 15 minutes before serving.

    Lamb covered with foil
    The Spruce

  7. Carve the lamb into slices against the grain. Plate, drizzle with the juices from the pan, and serve.

    Lamb carved into slices
    The Spruce

How to Store

Keep leftover lamb refrigerated and well covered for up to 3 days.

Recipe Variations

The flavoring that you choose for the marinade is the flavor that your outer crust and meat will have. For a smoother texture in your marinade, simply blend all of the ingredients at high speed until well incorporated. Fresh herbs and even their dried counterparts are great complements to lamb, but other flavors can be used when marinating this butterflied leg of lamb:

  • Replace the mustard in our marinade with 3 finely chopped anchovies.
  • Use the zest of one small orange or lemon in addition to the rest of the marinade ingredients.
  • Make a marinade using 1/3 cup of sesame oil, 2 tablespoons of honey, 2 tablespoons of lemon juice, 2 to 3 tablespoons of chopped mint, 1/4 white wine vinegar, and salt and pepper to taste.
  • Try using 1/3 cup of olive oil, 1/3 cup of good quality balsamic vinegar, 2 minced garlic cloves, 1 shallot finely minced, and 1 tablespoon each of dried thyme, oregano, sage, and rosemary.

Should Leg of Lamb Be Covered When Roasting?

Roasted leg of lamb is typically cooked uncovered to allow the exterior to crisp a bit and prevent soggy meat. Lamb is often rested, covered, after being cooked—covering with foil during the rest helps to retain the meat's juices.

Why Does Lamb Become Chewy?

If lamb is overcooked it can become chewy. Cook lamb just until medium-rare or medium, 145 to 150 F on a meat thermometer, and let rest before slicing.

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