Roasted
Roasted leg, shoulder, saddle and rack of lamb are Sunday staples and they're easy to cook. Just add garlic, salt, pepper and some aromtic herbs or roast as it comes. Lamb cooks very quickly: it takes 20-25 minutes per kilo in a very hot oven (230-250°C or Gas Mark 8). Make sure you baste the meat regularly and it'll be nice and tender.

Grilled or pan-fried
Marinated lamb chops with a bit of olive oil and some herbs or spices are delicious grilled or barbecued. If you're grilling, go for a medium heat, and if you're barbecuing, don't put them over the really hot coals.

In stews, braised or sautéed
Lamb has a finer, more distinctive taste than mutton, which tends to be stronger. The shoulder and neck are the best parts to braise (brown in fat and simmer in a sealed container). For stews, cut the meat into cubes, fry gently in oil and then slow-cook along with vegetables, tomatoes, spices and a little liquid for between an hour and an hour and a half. 

Boiled
You can cook many parts of lamb in water or stock. You wouldn't normally use the best parts for this type of cooking; the neck and the part above the ribs are ideal. The key is to brown your cubed meat in oil with herbs and then add water, tomatoes and spices, cook for 20-30 minutes and then season with salt, pepper, lemon and parsley.

Milk-fed and salt-meadow lamb
Milk-fed lambs are raised on their mother's milk and are the equivalent of veal. They have a subtle flavour and very soft, tender, pale flesh. 
Salt-meadow lambs (raised on salt meadows near the sea) are in high demand because they have a very distinct taste. Britanny is particularly famous for them.