Substantial soups, often a meal in themselves, are frequently made on cold Scottish days. Three Scottish staples are Cock-a-Leekie soup, Cullen Skink and Scotch Broth.
Cock-a-Leekie. The key ingredients are named in the title – a cock (chicken) and leeks. The soup is rich and filling and is often served at a Burns Supper. This is not a soup to be made in a hurry; the cock is cooked whole with some of the leeks – suggested timings vary, but reckon on at least two hours. The bird is then removed from the broth, chopped up and returned to the pan for further cooking with a small amount of rice and the rest of the leeks.
Cullen Skink. Named after the Cullen in Moray which borders the North Sea. Key ingredients are smoked haddock, milk, onions and potatoes; some people choose to add leeks. Haddock which has not been dyed is meant to be best for this soup, for example Arbroath Smokies or Finnan haddock. The fish is usually poached to create a stock for the soup, in which the vegetables are cooked. The skinned and deboned fish is mixed with the vegetables and milk towards the end of cooking. The potatoes can be partially mashed to create a thick broth, or they can remain as substantial chunks creating a stew-like dish. Some people choose to add cream or condensed milk to the soup, making it rich but extremely filling.
Scotch Broth. This is a soup which has graced shop shelves in cans for as long as I can remember. As with all good Scottish cooking, the idea is to use up what you have so recipes can vary. Mutton is traditionally used – thrifty Scots would often cook the mutton joint in the soup, then take the meat out before serving the soup to use as a main course. I have also come across recipes with beef, chicken or lamb. Vegetables too can vary depending on what is left in the store cupboard; cabbage, carrots, leeks, onions and turnips are commonly used, vegetables diced/sliced in to small pieces. The stock is thickened using pearl barley (and sometimes dried peas or lentils) which are cooked slowly with the meat for about an hour before any vegetables are added. As Cullen Skink, where the haddock is initially poached whole, the main meat of the dish is initially cooked in one piece, then cut up towards the end of cooking; resulting in a thick and substantial broth.
If you are interested in Scottish cooking I would recommend A Year in a Scots Kitchen: Celebrating Summer's End to Worshipping Its Beginning. More than a recipe book, it has a lot of fascinating background information about Scottish food through the seasons.