Place lamb on a work surface, open side up. Drizzle the inside with oil then season with salt and pepper. Add the other stuffing ingredients. Close the lamb using cooking twine.
Preheat the oven to 425◦F (220◦C).
Spread the onion slices and herbs in a baking dish and place the lamb on it. Add broth.
Place the lamb in the oven. After 20 minutes, cover with aluminum foil, lower the oven temperature to 375 ◦F (190 ◦C) and cook for about 1 hour and 10 minutes longer or until desired doneness.
Chef’s Tip
You can put the vegetables around and add carrots if you don't want to stuff your lamb.