Easy Scottish Recipes: Cullen Skink Soup

Cullen skink is a hearty Scottish soup from the town of Cullen in Moray, made with smoked haddock, potatoes, onion, and milk. This straightforward version uses one pot for poaching the fish and cooking the potatoes, making a comforting meal without complicated techniques.

Ingredients

1 lb (450 g) undyed smoked haddock fillets, skin removed if needed
4 cups (950 ml) whole milk
1 cup (240 ml) water
1 lb (450 g) floury potatoes, such as russets, peeled and cut into ½-inch (1.25 cm) cubes
1 medium yellow onion, about 5 oz (150 g), finely chopped
2 tbsp (28 g) unsalted butter
1 bay leaf
¼ tsp fine salt (about 1.5 g), plus more to taste
¼ tsp ground black pepper (about 0.5 g), plus more to taste
⅓ cup (80 ml) heavy cream, optional
2 tbsp (8 g) finely chopped fresh parsley
1 tsp (5 ml) lemon juice, optional

Instructions

Prepare the ingredients. Cut the potatoes into even cubes so they cook at the same rate, and chop the onion and parsley. Check the haddock for any remaining pin bones by running clean fingers gently over the flesh; remove any you find with tweezers. Keep the fish refrigerated until you are ready to cook it. The 20-minute prep estimate includes peeling and cutting the vegetables and preparing the fish.
Soften the onion. Melt the butter in a heavy-bottomed soup pot over medium-low heat. Add the onion and cook for about 5 minutes, stirring often, until it is soft and translucent but not browned. If it begins to sizzle or color quickly, lower the heat; a gentle start keeps the soup mild and lets the smoked fish remain the main flavor.
Poach the haddock. Pour the milk and water into the pot, add the bay leaf, salt, and pepper, and slowly bring the liquid just to a gentle simmer, about 3 minutes. Do not let it boil hard, since milk can scorch and boil over. Slide in the haddock and poach gently for about 9 minutes, turning the pieces once if they are not covered by the liquid. Check the thickest part with a food thermometer: fish should reach the USDA FSIS safe minimum internal temperature of 145°F (63°C). Lift the cooked fish onto a plate with a slotted spoon. If the fillets are unusually thick, they may need a little longer to reach temperature.
Cook the potatoes. Add the diced potatoes to the warm poaching liquid. Keep it at a gentle simmer for about 15 minutes, stirring occasionally, until the cubes are easily pierced with a fork. Avoid a vigorous boil, which can break the potato pieces apart before they are tender. Remove the bay leaf. If the liquid looks especially foamy, skim off the foam with a spoon.
Flake and thicken the soup. While the potatoes cook, break the haddock into generous flakes, discarding any skin or bones. When the potatoes are tender, press a few cubes against the side of the pot with the back of a spoon; this thickens the broth naturally while leaving plenty of potato pieces intact. Stir in the fish and cream, if using, and warm gently for about 3 minutes. Do not boil after adding the cream. The soup should be steaming hot, creamy, and full of visible flakes of fish.
Season and serve. Taste before adding more salt, because smoked haddock can be quite salty. Add black pepper and the optional lemon juice to brighten the broth, then stir in most of the parsley. Ladle into warm bowls and scatter the remaining parsley over the top. If the soup thickens as it stands, loosen it with a small splash of milk or water.

Tips

Choose the fish with salt in mind. Undyed smoked haddock is a traditional choice and gives the soup a clean, smoky flavor; dyed smoked haddock also works. Salt levels differ between fillets, so start with the small amount listed and season only after the soup is assembled. If you cannot find smoked haddock, use another smoked white fish, such as smoked cod, knowing that the flavor will be slightly different.
Keep the heat gentle. A rolling boil can make milk catch on the bottom of the pot and can cause delicate fish to break into tiny pieces. Bring the milk mixture up slowly, then maintain a quiet simmer. A heavy pot and an occasional stir help prevent scorching.
Cut potatoes evenly. Pieces close to ½ inch (1.25 cm) cook predictably in the stated time. Larger cubes may need a few extra minutes; very small pieces can dissolve before the soup is finished. If the potatoes are not tender after 15 minutes, continue simmering and check every 2 minutes.
Adjust the texture to your preference. Mash only a few potatoes for a broth with distinct pieces, or mash more for a thicker, smoother bowl. Cream is optional: omitting it makes a lighter soup, while adding it gives the broth a richer finish. Do not add flour unless you specifically want a much heavier texture.

Serving Suggestions

Serve Cullen skink hot as a filling lunch or a simple supper. Thick slices of crusty bread, oatcakes, or warm rolls are useful for soaking up the smoky broth. A small green salad with a sharp vinaigrette makes a fresh contrast, particularly if the soup is served as the main course. For a more traditional Scottish touch, offer oatcakes alongside the bowls.

For a starter, serve smaller portions in warmed cups or bowls before a roast or another substantial meal. Keep garnishes simple: parsley, a little freshly ground pepper, and perhaps a few drops of lemon are enough. The soup is already savory and smoky, so strongly flavored toppings can overwhelm the haddock.

Variations

There are regional and household differences in Cullen skink; some versions are thicker, some use more milk, and some rely on the potatoes alone for body. This recipe mashes a few cubes into the broth rather than blending the whole pot, so it stays rustic. For a smoother texture, remove the cooked fish, blend some or all of the potato broth carefully, then return the flaked fish to the pot.

For a dairy-free version, soften the onion in 2 tablespoons (30 ml) of neutral oil instead of butter and replace the milk with an unsweetened oat drink or a light, unsweetened plant-based cooking alternative. The result will not taste exactly like the classic milk-based soup, and the broth may be less rich. Avoid sweetened or strongly flavored alternatives. Add a little more liquid if the soup becomes too thick.

If you prefer a stronger smoky flavor, replace up to ½ cup (120 ml) of the water with additional milk only if the fish is not already very salty, or use a slightly larger amount of smoked haddock while keeping the other ingredients the same. You can also add a small pinch of white pepper. Avoid adding bacon or other cured meat unless you want a distinctly different, saltier soup that moves away from the usual fish-and-potato character.

Storage and Reheating

Cool leftovers promptly and refrigerate them within 2 hours of cooking in a covered, shallow container. Cullen skink keeps for 3–4 days in the refrigerator. The potatoes may absorb liquid as the soup sits, so stir in a splash of milk or water before reheating. For the best texture, reheat only the portion you plan to eat.

Warm the soup in a saucepan over low to medium-low heat, stirring gently and taking care not to let it boil. Reheat leftovers to 165°F (74°C), checking with a food thermometer. You can also microwave an individual portion in a covered microwave-safe bowl, stirring once or twice so it heats evenly, and checking that it reaches 165°F (74°C). Freezing is possible for up to about 2 months, but the potatoes and milk may separate or become grainy when thawed. If you plan to freeze it, the texture is usually better if you leave out the cream and add it after thawing and reheating.

Frequently Asked Questions

What is Cullen skink?
Cullen skink is a Scottish soup associated with Cullen, a town on the northeast coast of Scotland. Its defining ingredients are smoked haddock, potatoes, and onion, usually cooked in milk. The name and recipe are widely linked with the town, but proportions and texture vary from cook to cook.

Can I make Cullen skink with fresh haddock?
Yes, but fresh haddock will not provide the characteristic smoky, salty flavor. You can cook it using the same method and season carefully, but the finished soup will be closer to a mild haddock and potato soup. A little smoked fish or a modest amount of smoked haddock mixed with fresh fish can bring back some of the traditional flavor.

Do I have to peel the potatoes?
No. Thin-skinned potatoes can be scrubbed and left unpeeled for a more rustic soup. The skins will change the appearance and add a little texture. Russets are usually peeled because their skins are thicker and the potato flesh breaks down readily to help thicken the broth.

Why is my soup too thin or too thick?
For a thin soup, mash a few more cooked potato cubes into the broth and simmer gently for a minute or two. For a thick soup, stir in milk or water a little at a time until it reaches the consistency you like. Remember that the potatoes continue to absorb liquid as the soup cools and rests.

Can I prepare it ahead?
Yes. You can chop the onion and potatoes a day ahead and keep them covered in the refrigerator; store cut potatoes submerged in cold water and drain and dry them before cooking. The finished soup can also be made ahead and refrigerated for up to 3–4 days. Reheat it gently to 165°F (74°C), adding a splash of liquid if needed.

Is cream essential?
No. Cream is an optional finishing touch, not a requirement. The milk and mashed potato already give the soup body. Leave out the cream for a lighter version, or add it for a richer finish; in either case, taste before adding extra salt because the smoked fish may provide plenty.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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