This dish is a Passover and Rosh Hashanah favorite in many Sephardic households, corresponding to the time when the largest supply of lamb is available.
The younger the animal, the more tender the meat and delicate the flavor. When choosing lamb, look for meat that is a lighter red than beef with a bright, pink color; a fine-grained texture; bright white fat; and soft pinkish bones. A darker color indicates a more mature animal. A whole shoulder of lamb weighs 4–6 pounds; a boned shoulder weighs about 30 percent less, 3–4 pounds. Since bone conducts heat, the cooking time for boned lamb is actually longer.