This slow-roasted boneless leg of lamb is roasted for 4 hours on a bed of vegetables. It's tender, easy to make, and serves a decent-sized crowd. This slow-roasted leg of lamb is made similar to slow-roasted lamb shanks in foil packets, however, everything is combined into one baking dish. Both recipes make a delicious, tender lamb infused with fresh garlic and herbs.
If you'd like a beef version of this recipe, check out this Mediterranean pot roast.
What I Love About This Recipe
I love that this one-pan meal has the starchy potatoes, carrots, celery, and boneless lamb leg all slow-roasting together. The flavor is incredible, the lamb is very tender, and this recipe serves a good-sized crowd. You can choose to make the lamb gravy or not, it's completely optional.
Ingredient Notes
- Chopped vegetables: I use celery, carrots, potatoes, and onion, however, other vegetables can be substituted. I recommend fibrous vegetables with long cook times for this low and slow lamb roast recipe.
- Boneless leg of lamb: I use the boneless leg of lamb roast (from Costco) that's about 4 to 5 lbs (around 2.2 kg). Substitute a similar-sized bone-in leg of lamb for the boneless leg of lamb if desired.
See the recipe card at the bottom of the post for quantities.
How To Make Roasted Boneless Leg of Lamb
Set the oven to 325 ℉ (165 ℃).
Peel and chop the carrots, potatoes, and onion. Wash and chop the carrots. Add chopped vegetables to the baking pan.
Keep the mesh string on the lamb roast to keep it together. Marinate the lamb with mashed garlic, lemon juice, and a dried Italian herb blend. Place the lamb roast on top of the bed of vegetables.
Add a layer of parchment paper and then tightly wrap with foil.
Bake at 325 ℉ (165 ℃) for 4 hours, completely covered the entire time with foil. After 4 hours, remove the parchment paper and foil from the oven.
Set the oven to broil. Uncover the lamb and broil for 3 to 5 minutes or until the top of the lamb crusts.
Pro Tip: I recommend removing the mesh string before broiling (unlike the photos) so the seasoning doesn't stick to the string.
Either serve the roasted boneless leg of lamb as is or prepare a lamb gravy using the leftover lamb drippings.
Pro Tip: Slice the lamb before serving so the meat doesn't dry out.
How To Make Lamb Gravy
Separate the lamb and vegetables from the juice using a slotted spoon to make the lamb gravy. Pour the lamb drippings through a mesh strainer to remove any large chunks remaining. Set the lamb drippings aside.
In a small pot on the stovetop, add butter on medium-high heat. Once the butter is melted, add flour. Whisk the butter and flour together for about 30 seconds or until thoroughly combined.
Add the strained lamb drippings, continuing to mix with a whisk. Remove from the heat once the lamb gravy thickens after about 1 minute.
Serve the lamb gravy on the side. Slice the lamb so it's easy to serve.
Tips and Tricks
Marinate the lamb ahead of time. Add the mashed garlic and lemon juice to the lamb about 2 to 4 hours prior to roasting.
Don't use any fat. Lamb naturally contains a high fat content, so added butter or olive oil is not necessary.
Chop the vegetables in large chunks. The vegetables cook for a long time, so larger size chunks hold up better.
Use fresh garlic. I highly recommend using fresh garlic and mashing it with a mortar and pestle for seasoning the outside of the boneless leg of lamb.
Variations and Substitutions
Use a bone-in lamb leg. If you would prefer a bone-in lamb leg, use one! Just make sure the bone-in lamb leg is about the same size, so the temperature and cooking times will be the same.
Season with fresh herbs. Substitute fresh herbs for dried herbs.
Use a different combination of dried herbs or no dried herbs at all.
Equipment
- Peeler for peeling the potatoes and carrots
- Chef's knife and cutting board for chopping the vegetables
- Mortar and pestle or garlic press for mashing the fresh garlic cloves
- Lemon squeezer for juicing the lemon
- 9" x 13" baking dish to roast the boneless leg of lamb
- Parchment paper and foil to tightly cover the lamb as it bakes in the oven
- Small stovetop pot for making the lamb gravy
- Whisk for whisking the lamb gravy
Storage
Store the lamb and roasted vegetables in an airtight container in the fridge for up to 4 days.
FAQs
Both types of lamb have pros and cons. A bone-in leg of lamb roasts with the bone, creating a very flavorful roast. The leftover lamb bone can be used for bone broth also. A boneless leg of lamb is easy to carve but lacks the added flavor of the bone roasting with the lamb roast.
When comparing two lamb leg roasts of the same weight, a bone-in leg of lamb cooks slightly slower than a boneless leg of lamb. If roasting the lamb leg at a low temperature for a long time, the roasting time is pretty much the same.
Delicious Lamb Recipes
Low and Slow Recipes
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📋 Recipe
Slow Roasted Boneless Leg Of Lamb
Ingredients
Roasted Lamb
- 4 to 5 lbs boneless leg of lamb
- 5 large carrots
- 5 celery stalks
- 4 medium potatoes about 1.5 lbs (or ¾ kg)
- 1 large onion
- 8 garlic cloves mashed
- 1 lemon
- 1 tablespoon dried herbs
Lamb Gravy
- 1 cups lamb drippings
- 2 tablespoons of butter
- 2 tablespoons of flour
- salt to taste
Instructions
Make the Roasted Boneless Lamb Leg
- Peel and chop the carrots, potatoes, and onion. Wash and chop the celery. Add the chopped vegetables to a baking dish and add some salt and pepper.
- In a large bowl, marinate the lamb with mashed garlic, lemon juice, dried herbs, salt, and pepper. Keep the mesh string around the lamb (if present), and spread the seasoning all over the outside of the boneless leg of lamb.
- Place the marinated boneless leg of lamb on top of the chopped vegetables. Add a layer of parchment paper, then add a layer of foil. Tightly close the foil so that the baking dish is tightly covered. Bake the boneless lamb leg in the oven at 325 ℉ (165 ℃) for 4 hours.
- Remove the foil and parchment paper. Remove the mesh string. Set the oven to broil. Put the baking dish in the oven set to broil for about 2 to 4 minutes or until the top of the lamb is browned.
- Remove from the oven and serve as is. Alternatively, make a lamb gravy to serve with the slow-roasted boneless leg of lamb and vegetables.
Make the Lamb Gravy
- Separate the lamb drippings from the roasted lamb and vegetables. I just use a slotted spoon and carefully move over the lamb and vegetables to another dish. Then using a mesh strainer, I pour the lamb drippings to remove any large chunks. Set the lamb drippings aside.
- In a stovetop pot, melt the butter on high heat. Once the butter has melted, add the flour. Whisk for about 30 seconds until combined. Add the lamb drippings while continuing to whisk together until thickened (about 1 to 2 minutes). Serve the lamb gravy separately.
Notes
- Carve the boneless lamb roast just before serving so it doesn't dry out.
Michelle H
Never having slow roasted a leg of lamb, I was concerned about the length of time it would be in the oven and if I would really be getting enough pan drippings for enough gravy-I was absolutely thrilled with the results. I made this using an already seasoned boneless leg of lamb (rosemary and garlic from Aldi), so I only had to drizzle some lemon juice over the top along with adding a fresh herb bundle of oregano and thyme. My lamb weighed just under 2.5lbs so I checked it after 2 hours and all told had it in the oven about 2.5hrs. I added a little finely diced cooked carrot and onion to the pan dripping gravy and it was delicious. This will definitely be my new favorite way to cook my boneless leg of lamb! Thank you, Lily, for putting this out there to be googled by home cooks like me who look for tasty ways to put dinner on the table:)
Lily
Thank you so much for the comment Michelle! I need to try the Aldi lamb leg.. its wonderful that it’s pre-seasoned. If you like lamb shanks- the lamb shank foil packet is great tender recipe too.
Stephanie
Tender and delicious!
Lily
Thanks for the comment!