Step 1

Preheat the oven to 350F. Place the potatoes into a large casserole dish or roasting pan. Drizzle with olive oil and season generously with salt, pepper and herbs. Use a spatula to toss the potatoes in the seasonings, until well coated.

Step 2

In a small bowl, prepare the spread for the lamb: mix together the mustard, olive oil, thyme, rosemary, garlic, salt and pepper. Add more oil as needed until the sauce is creamy.

Step 3

Next, prepare the lamb. Trim off any extra thick pieces of fat. Using a sharp knife, score the fatty layer that surrounds the leg of lamb, taking care not to go too deep. Watch mt video recipe to see how it's done. Using your hands, rub the prepared spread all over the leg of lamb, making sure the meat is well seasoned all over. If using boneless leg of lamb, season the inside of the leg where the bone as been removed.

Step 4

If using boneless leg of lamb, season the meat all over, then use kitchen twine to truss the meat; the leg meat should be snugly together. Trussing the meat will ensure it cooks more evenly. Watch my video to see how it's done.

Step 5

Arrange the leg of lamb over the seasoned potatoes. Roast uncovered in the preheated oven at 350F/177C for 1 1/2 to 2 1/2 hours, until the internal temperature reaches 135F/57C for medium doneness. For medium-well, roast the lamb to 145F/63C. Bone-in lamb will take slightly longer. Timing also depends on size of the leg. Once the meat is done, allow it to rest in the casserole pan for 15 to 20 minutes before slicing using a sharp carving knife. Make sure to remove any kitchen twine before slicing!