Amazing Roasted Boneless Leg of Lamb with Creamy Horseradish Dipping Sauce

The perfect main dish for Easter, Christmas, or any Holiday meal this Roasted Boneless Leg of Lamb is easy to prepare and a total show stopper! With minimal prep work, a simple garlic mixture for coating, and a two ingredient dipping sauce this is a great and impressive dish to make for friends and family!

This post may contain Affiliate Links.

Boneless Lamb Roast Recipe

A leg of lamb is a great option for a holiday meal. For many years a leg of lamb has always been our family’s go-to meal for Christmas dinner.

For a long time I would always buy the leg of lamb with the bone still attached and then I discovered how much better the boneless leg of lamb was when I couldn’t find a bone-in version.

They are the same cut of meat yes but I found once the bone was removed the roast got a much more even cook. Not only that but it also easier to cut and serve as well.

If you are looking to make a different cut of lamb try this lamb breast or grilled rack of lamb.

Through the years I also found that what a lot of lamb roast recipes are missing is a dipping sauce. Especially for those who are trying it for the first time, the dipping sauce helps the tasting of a new food be way less intimidating. So I developed a creamy horseradish sauce that is super simple, like 2 ingredients and some water simple that helps elevate this meal to the next level.

Now the first time cooking lamb can be super intimidating. So I will try to go through as much detail as I can in the post as well as leave as many tips and answer questions as I can.

I mean I get it you are spending $35-45 on this roast, I don’t want you to mess it up!

So let’s start with what you need.

Ingredients

• Boneless Leg of Lamb – Most stores you are going to find the size to be from 2.5 to 3.5 pounds. Now if you are buying a leg of lamb not during a holiday like Christmas or Easter they might be hard to find. I have had luck at specialty stores, like a local butcher grocery where I live and the nationally known Whole Foods. At my local butcher the size of the boneless leg of lamb is consistently about 2.5 pounds. Talking to the butcher at Whole Foods he told me that all of there boneless leg of lambs average out at about 3.5 pounds. Any size you can find will work. I will also note that especially if it isn’t during the holidays the leg of lamb might not be on display. When I was at Whole Foods I had to ask because they didn’t have it in the display case but the butcher had some available in the back and got it out for me.
• Garlic – To help with the flavorful topping! I call for about 6 garlic cloves here and it yields a good amount of garlic but with out being too much.
• Olive Oil – For this recipe since it is a nice roast that depends on just a few nice ingredients I recommend using a nicer Olive Oil. A lot of cheap olive oils on the shelves at the grocery can be rancid, so try to use one that has a good taste when you try it raw on it’s own. My personal go-to is California Olive Ranch 100% California Grown, not an ad just a huge fan.
• Dijon Mustard – A little Dijon Mustard to help with the flavor and creaminess of the topping for the lamb.
• Kosher Salt – I recommend only using kosher salt for this recipe, kosher salt varies from table salt in the way the flakiness and salt crystals are formed, so the way that kosher salt dissolves into the dish is going to be different from how table salt would work. In a pinch you can use sea salt. My favorite kosher salt is Diamond Crystal Kosher Salt.
• Fresh Rosemary & Thyme – I find the combo of these to herbs to be a delicious power couple of flavor. They bring the right herb taste to the roast lamb without being overpowering.
• Sour Cream – For the dipping sauce. This is the base that the horseradish will be added to.
• Prepared Horseradish – A few scoops of prepared horseradish into the sour cream is essentially all the dip is, some water will be added to thin it out. I will note that amount I use is fairly light, I used just enough for some flavor and that my kids still enjoyed it. If you and the people you are serving it too are big fans of horseradish go ahead and add a little more tea your liking.

Note: Kitchen twine is needed for this dish.

For a complete detailed list of the ingredients continue towards the bottom of the page.

Instructions for Cooking Boneless Leg of Lamb

Preheat your oven to 350º F. Line a sheet pan or roasting pan with aluminum foil.

Prepare the topping for the lamb by adding the garlic, olive oil, dijon mustard, kosher salt, rosemary, and thyme to a single serve blender.

NOTE: If you don’t have a single serve blender you can attempt to make in in a full size blender or food processor but since the amount going into the blender isn’t every much you might have trouble… you could double the amount of the garlic sauce in order to blend it smooth and just not use all that extra sauce. Or you can also just mix everything by hand, albeit it might take a bit longer and not be quiet as smooth, if you are proceeding this way just ensure that the garlic is finely minced as well as the herbs, in a bowl whisk everything together to get a nice sauce.

If you are using the single serve blender pulse together until the garlic mixture becomes smooth, since it is a thick mixture you might have to scrap down the sides often and keep pulsing the blender until it is a thick yet mostly smooth sauce.

Carefully remove the netting from the lamb while keeping the roast together in the shape it came in as much as possible. I chose to remove the netting for this recipe because I think it gets in the way of having a nice outside crust on the roasted boneless leg of lamb. The netting is there to keep the roast together where the butcher took out the leg bone. Further down you will see a photo with dashed lines where you are going to re-tie the lamb leg together gently with kitchen twine after spreading the garlic mixture on to the lamb.

Lay the lamb roast fat side up. Gently dry with a paper towel if needed.

With a sharp knife make diagnal scores in the fat about 1 inch apart in one direction and then matching perpendicular lines in the other direction, creating a grid pattern. Scoop the garlic mixture overtop the lamb and spread all over the top and sides, ensuring to get in the scores of the fat as well. 

Now carefully with kitchen twine as to not wipe off the garlic mixture grab a long length of kitchen twine and bring it underneath the long way and around the top of the lamb, tie together gently. Now on the short side take two lengths of kitchen twine and carefully go under and over the lamb roast about 1/3 of the way from the ends gently tying together. Paying extra attention on the short sides that you are keeping the open cut from the bone closed if possible. Tying the lamb this way with the twine will keep the lamb in a roast shape instead of ballooning out where the bone had once been without needing the netting.

Transfer to the oven. Cook 30 minutes for every pound.

How Long Do You Cook Boneless Lamb For?

Boneless Leg of Lamb Roasting Times per Pound	Minutes
2 lbs	60
2.5 lbs	75
3 lbs	90
3.5 lbs	105

At What Temperature is Boneless Leg of Lamb Done?

Use a meat thermometor to check the doneness.

Leg of Lamb Doneness	Temperature
Medium/Rare	145º F
Medium	150º-155ºF
Well	160º F

145º F will be medium-rare, 150º to 155º F will be medium, and 160º F will be well done.

Let the lamb rest for at least 10 minutes, gently cut off the twine before slicing to serve. Serve with the Horseradish Cream sauce below.

Use a trustworthy meat thermometer for checking the doneness of your leg of lamb, I love to use my Thermapen from ThermoWorks.

How to make Horseradish Cream:

Add sour cream, horseradish, and water to a small bowl. Stir to combine, taste adjust as needed. Cover and refrigerate until ready to use.

If you are making this Roasted Boneless Leg of Lamb you might like these side dishes to go with it:

• The BEST Classic Mashed Potatoes
• Easy Roasted Carrots with Dill
• Garlic Parmesan Mashed Cauliflower
• Rice Pilaf with Cranberries
• Homemade Au Gratin Potatoes
• Instant Pot Mashed Potatoes for a Crowd
• Homemade Green Bean Casserole with Bacon
• Roasted Pear & Pecan Salad

And make sure you are following me on TikTok, Instagram, and Pinterest, for all the latest recipes!