Chop ¼ cup almonds; set aside remaining almonds. Mix chopped almonds with next 6 ingredients in a small bowl. Spread inside of lamb with ½ of the herb mixture. Roll lamb into an even cylinder and tie at 2-inch intervals with butcher twine. Rub remaining herb mixture onto outside of lamb roast and press reserved sliced almonds onto herbs. Place in roasting pan and cook for 20 minutes.
Lower the oven temperature to 375°F. Add the water or broth to the roasting pan and roast for another 40 to 50 minutes, or until the thickest part of the lamb reaches an internal temperature of 140°F for medium. Take the lamb out of the oven and let the meat rest for 15 minutes. Cut off twine, slice and serve with roasted fingerling potatoes, if desired.