What Is Cullen Skink?

Cullen Skink is a thick, creamy soup of smoked haddock, potatoes and leeks, and it takes its name from the small fishing village of Cullen on the Moray Firth. The old county name is Banffshire, and the soup is still the dish people expect when they sit down to eat on that stretch of the north-east coast. The word "skink" is an old Scots term for a broth or a shin-based soup, so Cullen Skink is, quite literally, the broth of Cullen.

Its origins are thoroughly domestic rather than grand. A household would have a piece of smoked haddock — a valuable thing, not to be wasted — and would stretch it across a meal with potatoes, an onion or a leek, and milk. What came out of that economy was a soup with real depth: smoky, saline, faintly sweet from the alliums, and thick enough to stand a spoon in. It is one of the clearest statements of north-east coast cooking, and it rewards being made properly rather than quickly.

The Ingredients That Matter

Four things carry the dish. Get them right and the method is almost forgiving; get them wrong and no amount of butter will rescue it.

• Smoked haddock — naturally smoked, ideally from the cold-smoking tradition associated with the north-east. Look for pale cream or light gold flesh. The bright yellow dyed fillets are traditional in some shops and perfectly usable, but the dye adds colour rather than flavour.
• Floury potatoes — Maris Piper, King Edward, Kerr's Pink or similar. Waxy salad potatoes stay firm and leave you with a thin, disappointing broth. You want potatoes that break down and thicken.
• Leeks and onion — older recipes often call for onion alone. A generous leek plus a smaller onion gives sweetness and a gentler finish than onion by itself.
• Whole milk and butter — semi-skimmed works, but whole milk carries the smoke better and gives the soup its characteristic body. A knob of butter stirred in at the end is not optional in most Scottish kitchens.

Beyond that you need water or a light unsalted stock, white pepper, salt to taste, and a handful of chopped chives or parsley. That is the whole list.

Choosing and Handling Smoked Haddock

Smoked haddock varies enormously in saltiness. A lightly smoked, modern fillet needs no soaking at all; a heavily salted, traditionally cured piece will make the soup inedible if you use it straight from the wrapper. Taste a sliver raw, or poach a small piece and taste it, before you commit. If it is fierce, soak the fillet in cold milk for twenty minutes to half an hour, then pat it dry.

Never boil smoked haddock. Boiling tightens the flesh and drives out the flavour into the water. Poach it gently in milk — barely a shiver on the surface, never a rolling boil — for six to eight minutes, until the flesh flakes under light pressure. Lift the fish out, flake it into large pieces and set it aside. Keep that milk. It is now smoky, savoury and slightly salted, and it is the backbone of the finished soup. Discard the skin and any stray bones at this point.

A Practical Method

This makes enough for four as a starter or two to three as a substantial main course.

• Melt a good knob of butter in a heavy pan and soften one large sliced leek and one chopped onion over a low heat for eight to ten minutes. Do not let them colour; you want sweetness, not caramel.
• Add roughly 500g of peeled, diced floury potatoes and about 500ml of water or light unsalted stock. Simmer for fifteen minutes or so, until the potatoes are completely tender. Add a little more liquid if it looks tight.
• While the potatoes cook, poach 400g of smoked haddock in 600ml of whole milk as described above, then lift out and flake the fish.
• Crush a few of the potato pieces against the side of the pan with the back of a spoon. This is what thickens the soup. Leave the rest whole so there is texture.
• Add the flaked fish and the reserved poaching milk. Warm through over a low heat without boiling, then season with white pepper and salt if needed.
• Finish with a final knob of butter and a scatter of chives.

Serving, Storing and Variations

Serve it hot in deep bowls with oatcakes, buttered bannocks or good soda bread. The soup thickens considerably as it stands, so loosen it with a splash of milk when you reheat it — gently, over a low heat, never at a boil. It keeps for two days in the fridge, and it freezes acceptably, though the potatoes soften further on thawing.

Variations exist all along the coast. Some cooks use onion only, some add a spoonful of cream at the end, and a few grate in a little nutmeg or mace. Others stir through a rasher of bacon for extra savour. All are within the spirit of the dish, provided you keep the smoke and the salt in balance.

Cullen Skink in Scottish Food Culture

This is fishermen's food that became celebration food. It appears on St Andrew's Night menus and as a first course at Burns suppers, where it makes a warming alternative to cock-a-leekie. But its truest setting is a kitchen on a cold, grey afternoon, with the rain coming in off the sea and a pot of soup on the hob.

What makes Cullen Skink worth learning is how much it says with so little. It belongs to a coastal tradition of smoking and preserving fish — the same tradition that gives us Arbroath smokies and the haddock of Findon — and it turns a modest amount of that precious fish into something generous enough to feed a family. Make it with attention to the smoking and the seasoning, and you are cooking a piece of the north-east coast, wherever your kitchen happens to be.