Langoustines (aka Norway Lobsters) are orangey-pink saltwater crustaceans that look like very small lobsters, or large crayfish. They'll grow up to 9 inches long (25 cm.) They have a real head, and two claws. They are found in both the Atlantic and the Mediterranean. They are more readily available in the UK and Europe than they are in North America.
That, however, not has stopped the usual "shrimp" terminology confusion from reaching North America anyway with the term "langoustine", as it has with all the other shrimp terms. Foodies and restaurants have decided to start calling any really large shrimp "langoustine", which being a French term naturally sounds fancier -- and more expensive.
When a Langoustine is dead, its pink tail will start to turn to black. Many commercially-caught Langoustines (particularly those caught by trawler) are treated with sodium metabisulphite to help the tails hold their pink colour for up to 4 days. A female Langoustine with roe in it is described as being "berried."
To eat a whole one that comes to you unshelled, all you really eat is the tail. Pull off the head, claws, legs and shell, and discard those.
They are available fresh or frozen. Their flesh loses a bit of its sweetness when frozen.
When the tails of Norway Lobsters are cut off, shelled and sold on their own, these are called "scampi" in the UK. The meaning of Scampi is starting to get confused in the UK, though, through American influence. See main entry on Shrimp.
The head and the claws are discarded; just the tail is served (as is also the case for Rock Lobster.) While the tail of a Rock Lobster is called a "Lobster Tail", the tail of Langoustines is referred to as "scampi."
Easily gets tough with overcooking. If the Norway Lobster has been frozen, plunge into boiling water for a few seconds. If fresh, it can be cooked in simmering water for a maximum of 10 minutes, though fresh ones are often just fried (5 to 6 minutes) or grilled or broiled (5 to 8 minutes).
There are many different ways to cook them. One of the nicest is one of the simplest: split them in half, brush with melted butter, and pop them under the grill/broiler.
The colour doesn't change much after cooking.
Allow 4 to 6 shell-on Norway Lobsters per person as a starter.