Cullen skink. Not a promising name for a soup, in all honesty – I think Dickens missed a trick by not borrowing it for one of his villains – but one sniff and you'll be won over. Stuffed full of warming wintery ingredients like smoked fish and starchy potatoes, made rich and comforting with milk or cream, it never fails to cheer, even in the darkest days of January. (Unless, I admit, you're sitting upwind of someone else's helping, in a badly ventilated office, with only a meanly filled, heavily chilled turkey sandwich for company. Then you might feel, with some justification, that cullen skink is as malevolent as it sounds.)
About that name: Cullen is, of course, a fishing town on the Moray Firth, an inlet popular with haddock, while "skink" has a more puzzling history. The New York Times claims it comes from the Middle High German word for a weak beer, which seems to make some of sense for a thin soup, but the Oxford Companion to Food counters that it's a variation of the German "schinke", or ham, denoting a shin specifically: "so the archetypal skink is a soup made from shin of beef".
Cattle perhaps being more valuable than fish in coastal regions, the locals adapted the idea to suit their own ingredients – and I'm very glad they did. Smokier and more assertive than American chowder, heartier than classical French bisque, it's one of the world's finest seafood soups.
The overwhelming flavour of cullen skin is smoked fish – haddock traditionally, but, as Hugh Fearnley-Whittingstall and Nick Fisher point out in the River Cottage Fish Book, just about any smoked white fish will do – so it's important to make sure that flavour is a good one.
Most recipes simply call for smoked haddock, with some adding "preferably undyed" – the taste is generally exactly the same, though obviously all that yellow colouring adds nothing positive to the nutritional content – but Stirling-born Nick Nairn specifies Arbroath smokies in his Great British Menu recipe.
Smokies are headless, gutted haddock, hot smoked over wood in the traditional fashion, and they're not easy to track down, but the smell when I finally get my mitts on a couple of pairs is enough to convince me they're probably worth the shoe leather. While I love their distinctive wood-smoked flavour and creamy texture, they overpower the soup, giving it an unpalatable acrid character. Save your precious smokies for somewhere they'll be better appreciated.
The soup base
Although cullen skink relies upon a certain amount of milk or cream to give it richness, when and how much to add varies wildly. Mark Hix, for example, gives a recipe in British Regional Food which involves cooking the ingredients in fish stock, and stirring in a couple of tablespoons of cream at the end. Although the stock cube I've used is rather overpoweringly fishy, the result is nice enough but lacks the comforting creamy sweetness I associate with this kind of soup. I also think the haddock, which has been simmered for 15 minutes, has gone a bit rubbery, which is a shame.
Nick Nairn also uses stock as a base, but this time it's homemade using Arbroath smokies (which, at £8 a pair, is no mean investment) along with white wine, leeks, fennel and onion. He adds this to softened onions, leeks and some boiled potatoes plus another couple of fish, simmers for 10 minutes, then blends with milk and cream before serving. A third smokie, flaked, become a garnish. This means the soup has the distinctive, smoky flavour of the fish, while the garnish shows off their delicate texture – but, as previously mentioned, the finished result is a sad waste of good smokies.
Sue Lawrence, meanwhile, makes a quick fish stock by simmering the haddock in water, then removing it and cooking the vegetables in the same water – the milk is added at the end. This is lovely – silky, rather than thin, and creamy without being off-puttingly rich (after all, this is a Scottish fishwives' dish).
Hugh Fearnley-Whittingstall and Nick Fisher poach their fish in milk, and, once it's cooked, add this milk, along with the potatoes, to some fish stock and sautéed onions, and simmer the two together. Although the milk has already been heated, somehow it begins to separate slightly, giving the finished soup a distinctly unattractive appearance.
Gary Rhodes gives the stock a miss completely in his New British Classics recipe, instead poaching the fish in milk, then cooking the vegetables in the same milk, and topping off with cream. It's utterly delicious – the fish has flavoured the milk beautifully – but so rich that I can only imagine eating it in tiny, restaurant portions, rather than the big steaming bowls I think cullen skink deserves.
Potatoes provide the filling bulk in a cullen skink: the New York Times suggests that canny Scottish cooks often use leftover mash, and indeed, many of the recipes online contributed by home cooks echo this practice. As I never leave any mash lonely and unloved in the bottom of the dish, I have to make some especially for the occasion, and then, as the recipe from the Potato Council counsels, whisk them into the finished soup. It does the job of thickening it, but I miss the chunks of potato in the other soups.
Without any mashing at all, however, the soup will be thin, and lack vital warming properties. Hugh and Nick suggest roughly mashing some of the potato against the side of the pan if you'd like to thicken it slightly, while Mark Hix purées a ladleful and then stirs it back into the pan. Neither of these have much effect – I prefer Sue Lawrence's suggestion of roughly mashing the entire contents of the pan before adding the fish, which leaves a few chunks intact and suspended in a heartily textured broth.
Nick Nairn's recipe purées all the spuds, resulting in the same rather boring consistency as the mashed potato version, save for the flakes of smokie. Gary, however, blanches half the potato chunks separately, then adds them to the liquidised soup along with the haddock. It's a bit thick for my taste, but I like the contrast between the smooth soup and the chunks of potato and fish and, as I'm using a quick stock, this should help thin it down slightly. If you don't have a blender, mashing it as Sue does is another perfectly good option.
Mark Hix says that his host on a fishing trip in Aberdeenshire left the skin on his potatoes, which I'm always a fan of with soup: it gives a more intense flavour. Nick Nairn boils his in their skins, presumably for this reason, then peels them, but I think this is a bit pointless – if you're not cooking for Michel Roux Jr himself, then leave them on. Extra nutrients.
Although alliums are essential for adding aromatic depth to a cullen skink, opinion is divided between leeks and onions – Hugh and Nick call for a vast quantity of the latter, commenting that "we find cooking them down to a rich, sweet mass gives the soup a really wonderful depth of flavour". They're right, but onions can beat even pungent smoked fish into submission: this is more like onion soup with a hint of haddock.
Mark Hix uses just leeks in his soup, which I think is a shame, because the sweetness of onions makes a lovely contrast to the savouriness of the fish. Leeks do bring a nice green freshness, however, so a mixture of the two, as recommended by Gary Rhodes, seems to be the best option. Shallots, as used by Nick Nairn, are too delicate in my opinion, and as for garlic, well, it's just plain wrong here.
Sue Lawrence suggests that "Jerusalem artichokes are also wonderful in this soup instead of potatoes", so I substitute them in her recipe. I like the sweet, earthiness they bring to the soup, but they don't thicken it as well as the potato, whose starchy creaminess is a better foil to the strongly flavoured fish.
Gary finishes his skink with a squeeze of lemon juice, which cuts through the dairy richness, but I don't think it adds anything to a lighter version. And I prefer the chives Sue Lawrence suggests to the chopped parsley used by Mark Hix; they're a lovely complement to those leeks and onions.
Perfect cullen skink
Cullen skink is one of Britain's best soups: full-flavoured, hearty, and comfortingly creamy, it's just the thing to warm your cockles after a hard day's work on the Moray Firth – or even at the office.
500g undyed smoked haddock, skin on
A bay leaf
Knob of butter
1 onion, peeled and finely chopped
1 leek, washed and cut into chunks
2 medium potatoes, unpeeled, cut into chunks
500ml whole milk
Chives, chopped, to serve
1. Put the fish into a pan large enough to hold it comfortably, and cover with about 300ml cold water. Add the bay leaf, and bring gently to the boil. By the time it comes to the boil, the fish should be just cooked – if it's not, then give it another minute or so. Remove from the pan, and set aside to cool. Take the pan off the heat.
2. Melt the butter in another pan on a medium-low heat, and add the onion and the leek. Cover and allow to sweat, without colouring, for about 10 minutes until softened. Season with black pepper.
3. Add the potato and stir to coat with butter. Pour in the haddock cooking liquor and bay leaf, and bring to a simmer. Cook until the potato is tender.
4. Meanwhile, remove the skin, and any bones from the haddock, and break into flakes.
5. Lift out a generous slotted spoonful of potatoes and leeks, and set aside. Discard the bay leaf. Add the milk, and half the haddock to the pan, and either mash roughly or blend until smoothish.
6. Season to taste, and serve with a generous spoonful of the potato, leek and haddock mixture in each bowl, and a sprinkling of chives.
Is cullen skink Britain's finest fish soup – and why, as an island nation, do we not have more great examples? Or do clam chowder, or bouillabaisse float your boat instead?