In the United States, “lamb” refers to both a sheep less than twelve months of age and to the meat from that same animal. “Mutton” is the meat of a sheep older than one year. Mutton is much rarer in the USA because lambs are far more popular for meat and only breeding stock is kept past one year of age.
In the United Kingdom, “yearling lamb” or “hogget” refers to sheep twelve to twenty-four months of age. “Mutton” is the meat from any sheep older than that, though in India and parts of Asia “mutton” refers to goat meat.
Lamb meat is something of a status symbol, while goat meat is seen as something for the poor. This is because it takes more resources to keep sheep. They are grazers and eat grass, and so must be provided with lush open fields. Sheep are docile and have no horns, and therefore need shepherds to guard them.
On the other hand, goats are browsers. They eat leaves, twigs, and almost anything else. They’re wily and independent and have horns for defending themselves. All this means it costs far less to feed and protect them.
In Christian parts of the world, the shepherd and his flock are symbols of the church and its followers. It has become a tradition to serve lamb at Eastertime, at least partly in remembrance of the sacrifice Jesus made for mankind.
The rather disparaging saying, “mutton dressed as lamb,” refers to someone who tries to appear far younger than they are. It comes from the dishonest practices of some old-time butchers who would try to make their meat look like it was pink, tender lamb instead of the dark, tough mutton that it was.
The younger the lamb, the more prized its meat. Most common is the meat from animals three to five months old, often called “spring lamb.”
Due to fatty acids in the meat, both lamb and mutton have a strong, gamey taste compared to beef or pork. The older the animal, the more pronounced the flavor, especially if has been fed grass rather than grain.
Removing the blood and fat from the meat removes most of the gamey taste. Trim off as much fat as you can, soak the meat in brine (salt and water) for an hour to draw out the blood, and rinse it thoroughly before cooking.
Lamb is a lean, tender cut of meat. Chops can be quickly pan-fried in a little oil or butter, while a leg of lamb can be oven-roasted in olive oil with spices to taste. Salt, pepper, and rosemary are commonly used to bring out the best flavor, and it’s an old tradition to serve lamb with mint jelly on the side.
Mutton does best when it’s cooked long and slow, either as a roast with plenty of olive oil or when diced and used in a soup or a stew with plenty of seasoning. Both goat mutton and sheep mutton are popular for use in curries, where the strong flavors of the spices blend very well with the flavors of the meat.