The tender leg of lamb is just what you need for a cold winter day. Roasted with vegetables, herbs and seasonings, it becomes incredibly moist, juicy and tasty. Serve this bone-in lamb with mashed potatoes for a world-class dinner this Sunday (or any day)!
Cooking with lamb seems daunting, but it certainly doesn’t have to be. My slow roast leg of lamb recipe is foolproof. With simple seasonings and ingredients, the hardest part is having to smell this delicious roast while cooking slowly in the oven!
When I make this dish, I use a 5.5-pound leg of lamb with bone. However, I’ve included instructions for the boneless and boneless leg of lamb so you can prepare this meal based on your favorite cut of meat, or whatever you might find at the grocery store. It’s delicious either way!
Serve with mashed roasted potatoes for a warm, buttery, creamy addition to your dinner. Some roasted vegetables would also be a great accompaniment, as would this wild rice pilaf.
INGREDIENT NOTES AND SUBSTITUTIONS
- Lamb – A protein with a strong, earthy taste. Its cooking time will vary depending on the choice of cut and weight.
- Onion, celery and carrots: When roasted with these vegetables, the meat absorbs all their slightly sweet and earthy flavors. The aroma of the three cooking together is unmatched! Yellow or white onions will work well in this dish.
- Orange – This fruit also contributes to the tempting aroma of the dish, helping to soften and add a degree of sweetness.
- Garlic: Have 15 to 20 cloves waiting for this dish. Due to its role in the sauce of the pan, it would not replace this ingredient.
- Rosemary: Pairs beautifully with meat, carrots, and orange, this herb has a complex flavor profile that pairs well with citrus, sweet, and spicy notes. Thyme or sage could be used, if needed.
- -We will roast the meat in a mixture of beef broth and water, helping it to moisten and tenderize
- Flour – Use this to thicken the leftover juice from the roast, creating a delicious pan sauce to serve with our dish.
HOW TO MAKE BONELESS LEG OF LAMB
- Preheat. Preheat your oven according to the baking instructions for the meat cut chosen below.
- Cut the vegetables. Cut the onion and orange into quarters. Separate and remove the skins from your garlic. Cut the celery into large, uneven pieces. Add to a pan along with carrots and rosemary.
- Season the meat. Sprinkle salt and pepper over the entire surface, pressing and massaging the seasonings on the meat. If you use bone, place the cut with the side of the bone facing up. Pour the meat broth and water into the roasting pan. Finally, pour the olive oil over the meat. Cover the pan with a large piece of foil.
HOW TO ROAST WITH BONE VS. BONELESS LEG OF LAMB
Boneless: Cook based on the weight of the meat. For a 4-7 pound cut, set your oven to 325°F. Adjust roasting times according to desired cooking
: Medium Rare: Cook for 20 minutes per pound, with an internal temperature of 145°F. Medium: Cook for 25 minutes per pound, with an internal temperature of
- Well done: Cook for 30 minutes per pound, with an internal temperature of 170°
Bone-In: Again, adjust based on how many pounds of meat you’re cooking. Set your oven to 300°F.
For a 4 to 4.5
lb. cut, cover the pan and cook for 4.5 hours. Remove the lid and toast for 45 more minutes to achieve a golden crust. If the meat weighs 6 to 6.5 pounds, roast covered for an additional hour.
HOW TO MAKE PAN SAUCE TO SLOWLY ROAST THE LEG OF LAMB
- Remove the vegetables. Transfer the pan, with all the juice and vegetables still inside, to your stove. Remove vegetables, rosemary and orange.
- Crush and boil. Using a crusher or wooden spoon, crush the roasted garlic. Mix this with the juices in the pan, then heat the juice until it starts to boil.
- Thicken with flour. In small increments, add the flour until everything is well combined. Then, simmer the sauce over low heat until it thickens.
Note: If your sauce is too thick, add small amounts of water until it has reached the desired consistency. Alternatively, mix the extra flour until it is as thick as you like. If desired, strain the remaining pieces of herbs into the mixture.
Is lamb’s leg better with or without bone?
There are many pros and cons to either. The bone may be tastier but more difficult to cut and serve. It also takes longer to cook. Boneless has a faster roasting time and is easy to carve, but this cut could be more expensive.
How long does it take to slow down the roast lamb leg
It takes about 5 hours and 45 minutes to slowly roast a boneless leg of lamb.
What can I serve with roast lamb?
I like to serve this dish with mashed potatoes! Since the vegetables used for roasting will be soft and overcooked, I recommend roasting a separate batch only if you want to enjoy them as a side dish.
Video: How to Roast Boneless Leg of Lamb in the Oven
Want to see the recipe in action from start to finish? Just watch the video below!
This recipe post, originally published on Kevin Is Cooking March, 2019, has been updated with new content, photos, and/or video in February 2023.