You’ve never had a Roast Boneless Leg of Lamb like this one, and we guarantee you’ll never make it any other way! This slow roast lamb uses a low heat method to tenderize the meat, followed by high heat for a golden crust. A sweet onion mustard infuses the leg of lamb and a bright zesty citrus salsa finishes it off. SO GOOD! Read more and watch the video for this one of a kind leg of lamb recipe below!
This roast boneless leg of lamb recipe along with all of our delicious lamb recipes on the website are in partnership with the American Lamb Board. Your one stop resource for everything American lamb. All opinions are my own.
I couldn’t be more excited about a new lamb recipe like I am today! Every single lamb recipe on our website, where it’s a family recipe that’s stuck around for generations. Or a classic lamb favorite that we’ve simplified for you to make. Or just a twist on our everyday dinners that we’ve elevated by using lamb. And so much more! All of these recipes are so special, unique and MUST try! But today’s roast leg of lamb is quite different.
We’ve researched so much and tried over 12 different ways to a perfect slow roast boneless leg of lamb. Some were old recipes without exact measurements which we had to improvise a lot on.
Others were classic everyday roasts and we played around with the spice and flavor profile. Some were boring. And others needed lots of tools and gadgets which made no sense. Then science came to play and our final winner was purely based on science.
Why You’ll LOVE this Roast Boneless Leg of Lamb
- It’s made with American Lamb, and that means it’s quality lamb. It’s the freshest possible lamb you can eat, the tastiest and sustainably grown locally.
- The type of lamb you buy makes a huge difference in the outcome of each recipe. So ALWAYS buy local American lamb.
- The science behind this technique ensure absolutely TENDER and juicy boneless leg of lamb. Every. singe. Time.
- You have full power over how well done you’d like the meat to be. Even at medium well and well done, the lamb is still JUICY!
- The way the meat is flavored is unlike traditional marinades. It has a rich sweet and umami combined without any mess.
- This roast boneless leg of lamb can be made with warm spices for a winter roast. It can also be served with a bright sauce or salsa like we did today for a bright taste.
- The recipe needs time, so with proper planning, you can have this ready in a breeze.
- This main dish can be served with endless sides, sauces or made into sandwiches.
- Did we mention, it’s HEAVENLY! Absolutely tasty and delicious lamb meat, that’s juicy and fool proof to prepare.
Ingredients You’ll Need
- Lamb. We used American Leg of Lamb for this recipe. You can buy the lamb boneless or ask your butcher to debone a leg for you. Likewise you can ask your butcher for how many pounds of meat you’re looking for. It depends how many people you’re serving.
- Our TIP is to make extra and use the meat for sandwiches, lunches and salads the next day! Also, ask the butcher (or you can do this yourself) about trimming off excess fat to your liking.
- Onions. The KEY difference here is that we cook the onions before slathering them on to the lamb. Cooked onions are sweeter, mellow and rich. And that’s the flavour we wanted the leg of lamb to taste like. Compared to raw onions (whole, grated or diced), this is the BEST!
- Rosemary. While you can use thyme or oregano, we love the richness of rosemary in this recipe. It compliments the sweet onions and mustard so well.
- Mustard. We used grainy mustard to flavour the lamb meat.
- Black Olive Paste. This is also known as Tapenade. It’s basically a paste of black Kalamata olives. While it’s not a usual ingredient, it adds the umami we were looking for. It’s salty, slightly briny, rich in olive notes and just perfect! You can use anchovies as a substitute, and no your meat will not taste fishy 🙂
- Citrus Zests. A combo of lemon and orange zests.These adds brightness and sweetness to the lamb.
- Garlic and Garlic Powder. Of course, we love garlic and lamb.
- Seasoning and Spice. You don’t need much spice here, basically salt and pepper. Of course we added a pinch of chilli flakes and some paprika.
- Citrus Salsa. This is bright, zesty, tangy and sweet, with a kick of spice. The icing on the cake as they say. Frankly, it’s optional, but highly recommended!
How to Roast a Boneless Leg of Lamb
Here’s another recipe for Boneless leg of lamb on our website. It’s stuffed with a Mediterranean fig pistachio filling, and roasted. While you can absolutely use that same technique, and it’s quicker, we urge you to try the one below.
Prepare the Flavoring
- Start by cooking the onions in butter.
- You want to cook the onions until they’re golden and have caramelized lightly. This is key for a sweet rich onion taste instead of a strong astringent one.
- Now add the garlic and cook that for just one minute. Remove the skillet off the heat completely.
- At that point add the remaining aromatics which flavour the lamb.
- This includes the mustard, the citrus zests, the black olive paste, herbs, spices and seasoning.
- Give that mix and set aside to cool.
- You need the mixture to be cooled completely before spreading to over the lamb.
Prepare the Boneless Leg of Lamb
- After the boneless leg of perfectly trimmed out of fat, season it liberally with salt and pepper. Make sure to season it on both sides.
- Press down the seasoning so it seeps in and flavours the meat well.
- Take the cooled onion mixture and spread it on the inside of the leg. Also make sure to press it down well so it sticks to the meat.
- Now you want to roll the leg. You don’t have to roll it into a cylinder, just into half is ok. Roll it in a way that it feels whole.
- Take a kitchen twine and follow the video for easy way to tie up the meat.
- You’ll start by tying up the leg by length and making a knot.
- Then you’ll take the thread and go in half inch or less intervals. Wrap the thread all around the meat and tie it at the point it meets the long initial tie.
- Continue in intervals until all the leg is wrapped up firmly.
- You can leave this mixture in the lamb for 10 minutes or up to 24 hours.
Roasting the Boneless Leg of Lamb
10.It is KEY to roast the leg of lamb over a wire rack. This ensures a perfect external crust on the meat.
11.Place aluminum foil for easy clean up on the baking sheet and then a wire rack on top.
12. Roast the boneless leg of lamb at VERY low temperature 275 degrees F. You want to roast it until you reach an internal temperature minimum of 135 degrees F and up to 150 degrees F for medium well.
13.Depending on the size of the lamb, this can take between 2-2.5 hours.
14.Remove the lamb and now set your oven to 500 degrees F. YES. That’s how you’ll continue to a perfect crust and get to reach a minimum of 145 degrees F internally. This is the recommended temperature by the USDA.
15.Roast at the 500 degrees F temperature for 10-15 minutes only until it sears up and looks perfectly crisp.
16.Set aside to rest and then slice beautifully.
What to Serve with Boneless Leg of Lamb
This could be the hardest part of the recipe! Because seriously what can’t you serve?
- Citrus Salsa. A bright combo of citruses (lemon orange, blood orange and grapefruit) segment and juices. Mixed with jalapeño and cilantro, to make the best salsa! Full recipe below.
- Potato Dishes. Our crispy oven roasted potatoes or the BEST mashed potatoes recipe.
- Veggies. Today we used our Air fryer Asparagus recipe, Rapini or sautéed green beans.
- Pastas. The Romesco sauce is phenomenal tossed with pasta too!
- Salads. Panzanella Salad would go lovely here!
Tips for Roasting Boneless Leg of Lamb
- Start with fresh and quality American lamb, it makes a difference to your recipe! It also makes a huge difference to buy local and support local.
- Cook the onions really well before proceeding with the remaining aromatics. This is KEY. Sweet caramelized onions have a richer and different flavor than the raw.
- When the onion mixture os ready, you need to make sure it has cooled down completely before spreading it over the boneless leg of lamb.
- Trim excess fat if you’d like a lighter tasting boneless lamb.
- Season the lamb liberally with coarse salt and coarse black pepper.
- Always press down the seasoning to seep it into the meat.
- Spread the onion mixture and likewise press it down well into the meat.
- Follow the video for the technique on tying the roast using a kitchen twine. It’s easy once you follow it.
- Make sure you tie the meat firmly. It doesn’t have to be a perfect shape, but it has to be firmly tied.
- 10.Roast SLOW. The low temperatures will activate the enzymes to tenderize the meat TREMENDOUSLY! You’ll end up with tender and juicy meat when following this technique.
- 11.Remove the meat 50 degrees before your desired final temperature.
- 12.Cut the twine before roasting at the higher temperature as it may burn.
- 13.When roasting on the high temperature, keep an eye on the lamb. You want a golden curst, you no longer need to be cooking it. The crust usually takes 10-15 minutes.
- 14.Always let the meat rest before slicing. This is the perfect opportunity to prepare the salsa or side dishes.
How to Store and Reheat Leftovers?
Leftovers, if any, can be stored in air tight container separately. The lamb meat slices or even whole can be stored for up to 5 days.
Leftovers make great sandwiches and wraps. They’re also great added over a salad or pasta dish.
To reheat leftovers, you can microwave the slices for 1 minute and a half. Or, wrap them in foil and reheat in the air fryer at 350 degrees F for 3-4 minutes.
How much lamb should I plan to serve per person?
This is ironically one of the most common questions. Ok seriously serve however one wants and keep leftovers for a happy day!!
On a serious note, usually 1/2 pound of meat person is the baseline. So a 6 pound boneless leg of lamb is good for 12 people.
What’s the best temperature to serve lamb at?
The USDA recommends cooking all cuts of lamb to 145℉, which is on the higher end of medium.
How do I know when the lamb is done?
The best way to know if your boneless leg of lamb is ready, or any cut is to use a meat thermometer.
How much more does the lamb keep going after it’s out of the oven?
Initially you’ll need to spare 50 degrees as the lamb will go back at a higher temperature for 15 minutes. And as it sits before slicing, you can estimate an extra 7-10 degrees.
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Roast Boneless Leg of Lamb
Ingredients
Lamb
- 6 pound boneless leg of lamb. Use American Lamb always.
- 1 Tablespoons coarse salt and pepper or to taste
Aromatic Mixture:
- 2 Tablespoons unsalted butter
- 1 onion Finely diced
- 6 cloves of garlic minced
- 1 Tablespoon black olive paste
- 3 tablespoons rosemary leaves minced
- 1 Tablespoon grainy mustard
- Zest of 1 lemon
- Zest of 1 orange
- 1 tablespoon paprika
- 1 teaspoon chilli flakes
- 1 Tablespoon Garlic Powder
Citrus salsa
- 1 grapefruit segmented
- 1 blood orange segmented
- 1 orange segmented
- 1-2 clementines segmented
- 1 lemon segmented
- Juice of 1 lime
- 1/2 red onion finely diced
- 1 jalapeno minced
- 1/4 cup cilantro minced
- 1 teaspoon salt
Instructions
-
Season the lamb heavily with salt and pepper, pressing down the seasoning well int the meat.
-
Cook the aromatics mixture.
-
In a skillet over medium high heat cook the onions in the butter for 7 minutes until golden and sweet and caramelized. Do not rush this step.
-
Add the garlic and cook for another 1 minute.
-
Remove the skillet off the heat and add in the remaining aromatic ingrediets.
-
Mix them well and let the mixture cool down entirely.
-
Spread the mixture evenly over the lamb and press it down.
-
Use a kitchen twine to tie up the boneless leg of lamb.
-
You’ll start by tying up the leg by length and making a knot.
-
Then you’ll take the thread and go in half inch or less intervals. Wrap the thread all around the meat and tie it at the point it meets the long initial tie.
-
Continue in intervals until all the leg is wrapped up firmly.
-
Cover the leg of lamb and let it sit in the mixture for 10 minutes while you preheat the oven or overnight in the fridge.
-
Preheat the oven to 275 degrees F.
-
Arrange some foil over a baking sheet and a wire rack on top of that. Place the meat over the rack.
-
Roast for 2-2.5 hours until a thermometer registers minimum of 135 degrees F.
-
Remove the leg of lamb and increase the heat to 500 degrees F.
-
Remove the kitchen twine.
-
Place the meat back at the high temperature oven for 10-15 minutes until golden crisp. The meat should look like it has a beautiful sear.
-
Remove the leg of lamb and tent it with a foil to rest.
-
Make the salsa : Mix all ingredients together and set aside.
-
Slice the lamb in half inch slices and serve with the salsa.
Recipe Video
Recipe Notes
Tips for Roasting Boneless Leg of Lamb
- Start with fresh and quality American lamb, it makes a difference to your recipe! It also makes a huge difference to buy local and support local.
- Cook the onions really well before proceeding with the remaining aromatics. This is KEY. Sweet caramelized onions have a richer and different flavor than the raw.
- When the onion mixture os ready, you need to make sure it has cooled down completely before spreading it over the boneless leg of lamb.
- Trim excess fat if you’d like a lighter tasting boneless lamb.
- Season the lamb liberally with coarse salt and coarse black pepper.
- Always press down the seasoning to seep it into the meat.
- Spread the onion mixture and likewise press it down well into the meat.
- Follow the video for the technique on tying the roast using a kitchen twine. It’s easy once you follow it.
- Make sure you tie the meat firmly. It doesn’t have to be a perfect shape, but it has to be firmly tied.
- 10.Roast SLOW. The low temperatures will activate the enzymes to tenderize the meat TREMENDOUSLY! You’ll end up with tender and juicy meat when following this technique.
- 11.Remove the meat 50 degrees before your desired final temperature.
- 12.Cut the twine before roasting at the higher temperature as it may burn.
- 13.When roasting on the high temperature, keep an eye on the lamb. You want a golden curst, you no longer need to be cooking it. The crust usually takes 10-15 minutes.
- 14.Always let the meat rest before slicing. This is the perfect opportunity to prepare the salsa or side dishes.
How to Store and Reheat Leftovers?
Leftovers, if any, can be stored in air tight container separately. The lamb meat slices or even whole can be stored for up to 5 days.
Leftovers make great sandwiches and wraps. They’re also great added over a salad or pasta dish.
To reheat leftovers, you can microwave the slices for 1 minute and a half. Or, wrap them in foil and reheat in the air fryer at 350 degrees F for 3-4 minutes.
How much lamb should I plan to serve per person?
This is ironically one of the most common questions. Ok seriously serve however one wants and keep leftovers for a happy day!!
On a serious note, usually 1/2 pound of meat person is the baseline. So a 6 pound boneless leg of lamb is good for 12 people.
What’s the best temperature to serve lamb at?
The USDA recommends cooking all cuts of lamb to 145℉, which is on the higher end of medium.
How do I know when the lamb is done?
The best way to know if your boneless leg of lamb is ready, or any cut is to use a meat thermometer.
How much more does the lamb keep going after it’s out of the oven?
Initially you’ll need to spare 50 degrees as the lamb will go back at a higher temperature for 15 minutes. And as it sits before slicing, you can estimate an extra 7-10 degrees.
This lamb recipe is a perfect Easter dish, the meat looks so juicy and tender. It makes me hungry!
I was nervous to cook lamb, but your recipe gave me the confidence I needed! It turned out beautifully tender, and the seasoning was spot on!
Wow! This lamb recipe is amazing! The spices added so much flavor and the salsa added the perfect finish. Our dinner guests loved it.
This lamb was so, so good. I loved how tender and juicy it was, and the spices were perfect.