Herb-roasted lamb and roast boneless leg of lamb with potatoes, lemon, and marjoram are both great recipes for boneless leg of lamb. The first recipe takes about three hours to make, while the second recipe requires marinating the lamb overnight.
To make herb-roasted leg of lamb, mince together 6 cloves of garlic, 1 tablespoon of salt, 1 teaspoon of pepper and 2 tablespoons of melted butter. Spread the mixture on the lamb to coat it completely, and leave it to sit at room temperature for at least 30 minutes. Mix 4 pounds of small potatoes with 6 cloves of unpeeled garlic, season with some sea salt and olive oil, and put them in the bottom of a roasting pan. Place the lamb on top the potatoes, and cook it for 1 1/2 hours at 450 degrees F.
To cook a roast boneless leg of lamb with potatoes, lemon and marjoram, make 1/2-inch-deep slits in the lamb, and put a garlic slice inside each slit. Coat with 1/2 cup of lemon juice. Mix 3 tablespoons coarsely chopped fresh marjoram, 5 tablespoons extra-virgin olive oil and 2 cloves crushed garlic, and coat the lamb with the mixture. Fold and tie the lamb with kitchen twine, and put it in the refrigerator for 12 to 24 hours. Remove the lamb from the marinade, sprinkle it with salt and pepper, and let it sit at room temperature for 45 minutes. Cut up 2 1/2 pounds of potatoes into bite-sized pieces, season them with salt and some olive oil, and put them in the bottom of a roasting pan. Roast for 30 minutes at 425 degrees F and then 40-45 minutes at 400 degrees F.