Browned on the outside and juicy in the middle, this Rosemary Garlic Roast Leg of Lamb can be prepared in the oven or on your grill. A tray of potatoes and vegetables catch all of the flavourful drippings as the lamb roasts above and the entire meal gets served with a tangy and bright homemade tzaziki.
What You Need for Rosemary Garlic Roast Leg of Lamb
Leg of Lamb: You can use bone-in or boneless for this Rosemary Garlic Roast Leg of Lamb – I used the latter because that’s what was available to me at the time.
Both have their advantages and downsides. Bone-in leg of lamb tends to deliver a juicier finished product, but it takes slightly longer to cook and can be trickier to carve. Boneless leg of lamb allows for the marinade to penetrate all sides of the meat, but requires additional trussing before roasting.
- Rosemary: If possible, use fresh rosemary here. It’s more aromatic and has a subtler flavour than the dried stuff. If you only have dried rosemary, use around 1/2 the amount called for in the recipe and wake the flavours up a bit by rubbing it between your fingers before adding it to the marinade.
Garlic: And lots of it! Lamb, particularly pasture-raised ones coming out of New Zealand and Australia, can have quite a pronounced flavour. Garlic helps tone things down a bit
and also packs a delicious punch.
- Lemon: Not only does lemon provide a beautiful citrus flavour, the acid helps tenderize the leg of lamb as it marinades.
- Oregano and Thyme: As with the rosemary, if you have fresh oregano and thyme, use them! I did not so I used the dried stuff.
- Dried Red Chili Flakes: These don’t add so much of a heat as they do a depth of flavour in this recipe. Think of them as a way to back up the spice from the black pepper.
- Vegetables: I often place a tray of potatoes and vegetables underneath the lamb so that they catch all of the flavourful drippings as it roasts. This time it was creamer potatoes, carrots and garlic. But you could do bell peppers, green beans, or fennel.
- Tzaziki: As the lamb roasts, whip up an easy homemade Tzaziki with some Greek yogurt or coconut yogurt if you’re keeping things Whole30 and Paleo. It pairs really well with the Rosemary Garlic Roast Leg of Lamb.
Rosemary Garlic Roast Leg of Lamb with Tzaziki
For the Tzaziki:
- 1 cup full-fat Greek yogurt
- Juice ½ lemon
- 2 small Persian cucumbers peeled, deseeded and finely chopped
- 2 cloves garlic finely chopped or grated
- 1 tablespoon finely chopped fresh dill
- 8 sprigs mint finely chopped, substitute 1 teaspoon dried mint
- ½ teaspoon dried oregano substitute 1 teaspoon finely chopped fresh oregano
- Kosher salt and freshly-cracked black pepper to taste
For the Roast Leg of Lamb:
- 6 cloves garlic finely chopped
- 1 tablespoon finely chopped fresh rosemary around 2 sprigs
- 2 teaspoons dried oregano
- 2 teaspoons dried thyme
- 2 teaspoons kosher salt
- 1 teaspoon dried red chili flakes
- ½ teaspoon freshly-cracked black pepper
- Juice and zest 1 lemon
- ¼ cup extra virgin olive oil
- 1 boneless leg of lamb around 4 pounds, substitute bone-in leg of lamb
- 1.5 pounds creamer potatoes
- ½ pound carrots cut into large pieces
- 1 large red onion cut into wedges
For the Tzaziki:
- In a bowl, combine all of the ingredients and stir to combine. Cover and refrigerate until ready to serve.
For the Roast Leg of Lamb:
- In a bowl, combine the garlic, rosemary, oregano, thyme, salt, chili flakes, black pepper, lemon juice, lemon zest, and olive oil. Stir to combine. Place the lamb into a bowl or tray, pour ¾ of the marinade overtop and massage to coat. Reserve the remaining ¼ marinade for basting. Cover and refrigerate 6 hours to overnight.
- Remove the lamb 1 hour before cooking and let it come to room temperature. Roll the lamb very tightly into a cylindrical shape and tie with butcher’s twine. In a roasting tray, combine the potatoes, carrots and onion.
- Preheat Traeger grill or oven to 500F.
- If using a Traeger, place the lamb, fat side-up, on the top rack and position the tray with vegetables directly underneath. If using an oven, place the lamb, fat side-up, directly onto the upper oven rack and position the tray with vegetables directly underneath. Alternatively, place the lamb on a wire rack and position it overtop of the tray with vegetables.
- Roast the lamb for 15 minutes, then drop the heat to 350F and continue cooking, basting every 45 minutes with the reserved marinade, until the lamb is browned on the outside and the thickest part registers 135F for a medium centre, around 2 hours total. If a darker crust is desired, broil the lamb for a couple of minutes longer or place it fat side-down on the grill to finish.
- Let the lamb rest at least 15 minutes before carving. Serve with the roast vegetables and tzatziki.