Cock

Cock-a-leekie soup is a Scottish soup dish consisting of leeks and peppered chicken stock, often thickened with rice, or sometimes barley. The original recipe added prunes during cooking, and traditionalists still garnish with a julienne of prunes. While it is called "Scotland's National Soup", it probably originated as a chicken and onion soup in France. By the late 16th century, it had made its way to Scotland, where the onions were replaced with leeks. The first recipe was printed in 1598, though the name "cock-a-leekie" did not come into use until the 18th century. Traditionally, the soup is made with broiler fowl and would not contain thickeners, or vegetables other than leeks. It would range from a clear stock to a green leek stock, with little flesh. The original cock a leekie is delicate and refreshing and difficult to make flavoursome whereas the more appetizing modern version which has more chicken, vegetable and thickener is closer to chicken soup or stew.

Source: Wikipedia