Slow Roasted Boneless Leg of Lamb is an elegant, impressive entrée that’s actually super easy to prepare with my step-by-step instructions! Lamb is marinated in an Asian-inspired mixture of oil, soy sauce, sherry, ginger, mustard and garlic, then slow roasted. The resulting meat is tender, juicy and will have your tastebuds dancing with delight!

Marinated and slow roasted leg of lamb

Slow Roasted Boneless Leg of Lamb

My mom’s marinade for steak and lamb is pretty infamous among our friends and family. Once you’ve tried lamb marinated in her delicious Asian-inspired mixture of oil, soy sauce, sherry, ginger, mustard and garlic, you’ll never want to eat it any other way. Mom used to leave the butterflied leg of lamb unrolled, marinate it and grill it. I find that carving is easier – and the presentation prettier – if you roll the butterflied leg and slow roast it. Searing it first – either in a cast iron skillet or on the grill – gives it a nice dark brown crust.

Serve this scrumptious Roasted Leg of Lamb with scalloped or roasted potatoes and asparagus for an elegant gathering almost any time of year.

Boneless Leg of Lamb Marinade Ingredients

There are only 6 ingredients in this amazing marinade, all of which should be available at most major grocery stores:

  • Vegetable oil (can also use canola oil)
  • Soy sauce (regular or low sodium)
  • Dry sherry (can substitute dry white wine – or my brother uses tequila!)
  • Dry ginger
  • Dry mustard
  • Minced garlic

Slow Roasting Boneless Leg of Lamb How-to

Time needed: 4 hours and 50 minutes.

Slow roasting meat ensures it comes out tender, juicy and full of flavor. Here’s how to slow roast this boneless leg of lamb:

  1. Prep lamb.

    Once you have marinated the lamb, remove it from the marinade and place on an oven-proof wire rack in a roasting pan. Let sit at room temperature for 1 hour.

  2. Preheat oven.

    Preheat oven to 300 degrees – use the “roast” setting if you have it on your oven.

  3. Dry and season lamb.

    Pat lamb dry with paper towel. Brush all over lightly with olive oil. Season with salt and fresh ground pepper. Wipe any drippings out of the bottom of the roasting pan and set aside (with the rack).

  4. Prep searing pan or grill.

    Coat a skillet (preferably cast iron) large enough to hold the lamb with vegetable oil and heat over high heat – or heat a grill to high.

  5. Sear lamb.

    When hot, sear the outside of the meat just until browned on all sides. Don’t turn too much.

  6. Roast lamb.

    Place seared lamb on the same rack in the roasting pan and roast for 40 minutes. Turn meat over and continue roasting until the internal temperature reaches 135 degrees for medium rare or 145 degrees for medium – takes around 1 1/4 to 1 1/2 hours.

  7. Rest roasted lamb.

    Remove from oven, cover loosely with foil and let sit for at least 10 minutes before serving.

Marinated and roasted leg of lamb

How to Store Slow Roast Boneless Leg of Lamb

Leftover lamb should be well wrapped and stored in the refrigerator. It will last up to 3 days.

Slow Roast Leg of Lamb FAQ

How long should you marinate lamb?

I recommend marinating lamb for at least 2 hours, up to 24 hours. You need enough time for the meat to start absorbing the marinade flavors. If you have tine, I recommend marinating it for the full 24 hours for this roasted lamb recipe.

Should you marinate lamb leg overnight?

Yes! I prefer marinating the lamb overnight for this recipe.

What should you season lamb with?

When slow roasting lamb, at a minimum it needs a coating of oil and a sprinkle of salt and pepper. You can add other seasonings – like a marinade, or chopped rosemary and a coating of Dijon mustard.

Does slow cooking lamb make it tender?

Yes, definitely. Slow cooking virtually any meat will ensure it comes out tender, provided you don’t overcook it.

What is the best temperature for leg of lamb?

I think 135 to 145 degrees is the best temperature for leg of lamb. If the temperature goes much higher, it can get dry and sometimes tough.

What is the lowest temperature you can cook lamb?

Rare lamb (red center, surrounded by bright pink) would be cooked to 120 to 125 degrees. So, that would be the lowest temperature.

How do you keep lamb moist when roasting?

The good news with leg of lamb is that it’s a naturally moist cut of meat. With this recipe, you don’t need to do anything beyond my directions to ensure it stays moist. Oh, and don’t overcook it – that will dry it out. When the internal temperature reaches 135 to 145 degrees, it’s done.

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Marinated and roasted leg of lamb

Slow Roasted Boneless Leg of Lamb

  • Author: by Lee Clayton Roper (Mom’s Marinade is in “A Well-Seasoned Kitchen®” by Sally Clayton and Lee Clayton Roper)
  • Prep Time: 5 mins
  • marinade and resting time: 190 mins
  • Cook Time: 95 mins
  • Total Time: 4 hours 50 minutes
  • Yield: 10 to 12 servings 1x
  • Category: Lamb, Entertaining, Gluten free
  • Method: Roasting
  • Cuisine: American
  • Diet: Gluten Free

Description

Boneless Leg of Lamb is marinated in an Asian-inspired mixture of oil, soy sauce, sherry, ginger, mustard and garlic, then slow roasted. The resulting meat is tender, juicy and will have your tastebuds dancing with delight!


Ingredients

Scale
  • 1/2 cup vegetable oil, plus more for searing meat
  • 1/2 cup soy sauce
  • 1/4 cup sherry
  • 2 teaspoons dry ginger
  • 2 teaspoons dry mustard
  • 1 large garlic clove, minced
  • 1 (5-pound) boneless leg of lamb, trimmed, rolled and tied (see Note)
  • Kosher salt
  • Fresh ground pepper

Instructions

  1. In a medium bowl, whisk together the oil, soy sauce, sherry, ginger, mustard and garlic. Place mixture in a large zip top baggie; add leg of lamb. Seal, turn to coat the lamb and place in the refrigerator to marinate for 2 to 24 hours. Turn occasionally.
  2. Remove lamb from marinade and place on an oven-proof wire rack in a roasting pan. Let sit at room temperature for 1 hour.
  3. Preheat oven to 300 degrees – use the “roast” setting if you have it on your oven.
  4. Pat lamb dry with paper towel. Brush all over lightly with olive oil. Season with salt and fresh ground pepper. Wipe any drippings out of the bottom of the roasting pan and set aside (with the rack).
  5. Coat a skillet (preferably cast iron) large enough to hold the lamb with vegetable oil and heat over high heat – or heat a grill to high. When hot, sear the outside of the meat just until browned on all sides. Don’t turn too much.
  6. Place the seared lamb on the same rack in the roasting pan and roast for 40 minutes. Turn meat over and continue roasting until the internal temperature reaches 135 degrees for medium rare or 145 degrees for medium – takes around 1 1/4 to 1 1/2 hours. Remove from oven, cover with foil and let sit for at least 10 minutes before serving.

Notes

Gluten free: use gluten-free soy sauce.

Tips on buying lamb: Boneless leg of lamb often comes rolled and wrapped in netting. Check to make sure the netting is ovenproof and safe for cooking. If not, remove and tie the lamb with kitchen twine. You can also ask your butcher to trim and roll a butterflied leg of lamb for you – make sure to ask for the internal fat to be removed. Also, ask for the shank end of the leg with the sirloin to be removed – the latter makes a better presentation. After the sirloin is removed, the remaining leg will typically weigh closer to 4 pounds, so factor that into your number of servings. You can chop the extra sirloin meat for use later in Clayton Family Lamb Curry (in A Well-Seasoned Kitchen®)!

Keywords: roasting, marinade for meat

Lee Clayton Roper

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I’m Lee Clayton Roper, and I’m passionate about making cooking and entertaining easy, elegant and fun. Here you’ll find scrumptious recipes, helpful tips and seasonal menus that will spark inspiration in your kitchen!
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