Irish Fish Soup: Creamy Haddock, Salmon and Potato Recipe

Irish fish soup is a creamy, coastal-style soup made with white fish, salmon, potatoes, aromatics and a little smoked fish for depth. Recipes vary by household and region; this version is hearty but balanced, with tender pieces of fish added at the end so they stay moist and distinct in the broth.

Ingredients

2 tablespoons unsalted butter (28 g)
1 tablespoon olive oil (15 ml)
1 medium yellow onion, finely diced (about 150 g)
1 large leek, white and light-green parts only, washed and thinly sliced (about 180 g)
2 celery stalks, finely diced (about 100 g)
2 garlic cloves, minced (about 6 g)
2 tablespoons all-purpose flour (16 g)
5 cups fish stock (1.2 L), preferably low-sodium
1 pound waxy potatoes, peeled if desired and cut into ½-inch (1.25 cm) cubes (450 g)
1 bay leaf
1 teaspoon dried thyme (about 1 g)
½ teaspoon kosher salt (about 3 g), plus more to taste
¼ teaspoon freshly ground black pepper (about 0.5 g)
1½ cups whole milk (360 ml)
1 cup heavy cream (240 ml)
12 ounces skinless haddock, cut into 1-inch (2.5 cm) pieces (340 g)
8 ounces smoked haddock, pin bones removed and cut into 1-inch (2.5 cm) pieces (225 g)
8 ounces skinless salmon, pin bones removed and cut into 1-inch (2.5 cm) pieces (225 g)
1 tablespoon fresh lemon juice (15 ml)
2 tablespoons chopped fresh flat-leaf parsley (about 8 g), plus a little more for serving

Instructions

Prepare the fish and vegetables. Check the fish for pin bones, then cut it into similar-sized pieces and keep it refrigerated while you start the soup. Dice the onion and celery, slice and rinse the leek thoroughly, and cut the potatoes into small, even cubes. Keeping the fish cold until it goes into the pot makes it easier to handle and helps it hold its shape.
Soften the aromatics. Melt the butter with the olive oil in a large, heavy-bottomed pot over medium heat. Add the onion, leek and celery and cook for about 6 minutes, stirring occasionally, until softened but not browned. Stir in the garlic and cook for 30 seconds. Sprinkle in the flour and stir constantly for 1 minute so it coats the vegetables and loses its raw taste. If the bottom begins to color, lower the heat; browned aromatics can make the soup taste toasted rather than gently savory.
Simmer the potatoes. Pour in the fish stock gradually while stirring to loosen the flour and prevent lumps. Add the potatoes, bay leaf, thyme, salt and pepper. Bring the liquid to a gentle simmer, then lower the heat and cook uncovered for 16 minutes, or until the potatoes are nearly tender when pierced with a knife. Stir from the bottom once or twice. Keep the soup at a quiet simmer rather than a hard boil, which can break up the potatoes and reduce the liquid too quickly.
Add the dairy. Stir in the milk and cream and warm the soup gently for 3 minutes. Do not let it boil vigorously after adding dairy; high heat can make the texture grainy or cause the cream to separate. Taste a spoonful of broth and adjust the salt lightly, remembering that smoked haddock and prepared fish stock can both be salty.
Cook the fish gently. Add the haddock, smoked haddock and salmon, distributing the pieces around the pot without vigorous stirring. Simmer gently for about 8 minutes, depending on the thickness of the pieces, until the fish is opaque and flakes easily. Check the thickest piece with a food thermometer: USDA FSIS gives fish a safe minimum internal temperature of 145°F (63°C). If pieces reach that temperature before the full time, turn off the heat rather than continuing to cook them.
Finish and serve. Remove the bay leaf. Stir in the lemon juice and parsley with one gentle fold, then taste and adjust the seasoning. Let the soup stand for 1 minute so the flavors settle, and ladle it into warm bowls, making sure each serving gets a mix of fish, potatoes and broth.

Tips

Rinse the leek well. Soil often hides between its layers. Slice it first, then swish the pieces in a bowl of cold water and lift them out so the grit stays behind. Drain well before adding it to the pot.
Choose the fish for the texture you like. Haddock is mild and flakes neatly; cod, pollock or hake work in its place. Salmon adds richness and color, but you can replace it with more white fish. Ask for skinless fillets and check carefully for pin bones before cooking.
Adjust smoked fish and salt together. Smoked haddock is traditional in many fish-soup styles but can be hard to find. If unavailable, use 8 ounces (225 g) extra fresh haddock and add ¼ teaspoon smoked paprika. That gives a gentle smoky note, though it will not reproduce the saltiness or concentrated flavor of smoked fish. Taste before adding extra salt.
Keep the pot gentle once fish goes in. Avoid vigorous stirring, which can turn the fillets into flakes before they reach the table. Fold carefully with a broad spoon, and use an instant-read thermometer instead of judging doneness only by appearance.

Serving Suggestions

Serve the soup hot in deep bowls with crusty sourdough, Irish brown bread or soda bread for dipping. The bread is especially useful for soaking up the creamy broth, so a slice alongside each bowl makes the meal more substantial without requiring another side dish. For something lighter, offer a simple green salad with a sharp vinaigrette; its acidity contrasts with the rich cream.

Finish each serving with chopped parsley, a little black pepper and, if you like, a small squeeze of lemon. Put lemon wedges on the table rather than adding a lot to the pot: diners can brighten their own portions without making the entire batch taste too tart. Serve the soup soon after cooking, while the fish is tender and the potatoes still hold their shape.

Variations

Use a different fish mix: Keep the total fish quantity close to 28 ounces (790 g), and combine sturdy white fish with a richer fish such as salmon or trout. Cod, hake and pollock are practical alternatives to haddock. Avoid very delicate fillets if you want distinct chunks, because they may break apart more readily during stirring.

Make it lighter: Replace the heavy cream with an equal amount of whole milk, or use ½ cup (120 ml) cream and 2 cups (480 ml) milk. The result will be less rich and slightly thinner. For a dairy-free version, use an unsweetened, unflavored oat or soy drink and a plant-based cooking cream; the flavor will change, and some products can separate if boiled, so keep the soup at a gentle simmer.

Make it gluten-free: Replace the all-purpose flour with 1 tablespoon (8 g) cornstarch mixed smoothly with 2 tablespoons (30 ml) cold water. Add the slurry after the potatoes are tender and stir while the soup simmers briefly to thicken, then add the dairy and fish. The broth will be a little glossier and less like a flour-thickened chowder.

Add shellfish or herbs: You can replace part of the fish with peeled raw shrimp, or add cooked mussel meat near the end just to warm through. If using raw shrimp, cook it until opaque and check that it reaches 145°F (63°C). Dill or chives can replace some of the parsley for a fresher herbal note, while keeping the lemon modest so it does not overwhelm the fish.

Storage and Reheating

Cool leftovers promptly and refrigerate them within 2 hours of cooking in shallow, covered containers. Keep the soup refrigerated for 3 to 4 days. The fish may become a little softer as it sits, and the potatoes can absorb some broth, so the texture will not be quite as delicate as when freshly made. If the soup thickens, loosen it with a splash of milk or stock when reheating.

For best quality, freeze the soup for up to 2 months in airtight freezer-safe containers, leaving a little room for expansion. Cream-based soups can separate slightly after thawing, and fish texture may soften; thaw overnight in the refrigerator and stir gently as it reheats. Warm only the portion you need in a saucepan over low to medium-low heat, stirring occasionally and avoiding a hard boil. USDA FSIS recommends reheating leftovers to 165°F (74°C); check the center with a food thermometer. Discard soup left at room temperature for more than 2 hours, or more than 1 hour when the room is above 90°F (32°C).

Frequently Asked Questions

Can I make Irish fish soup with frozen fish?
Yes. Thaw the fish completely in the refrigerator, then pat it dry before cutting it into pieces. Excess ice or water can dilute the broth and make it harder to keep the fish pieces intact. Do not thaw fish on the counter; keep it chilled until it is ready to add.

What fish is best for Irish fish soup?
Haddock is a useful choice because it has a mild flavor and forms tender flakes, while smoked haddock contributes a savory, smoky note. Salmon adds richness. Cod, pollock, hake or other firm white fish can replace haddock, and the recipe is flexible as long as the fish is cut evenly and cooked gently.

Can I make the soup ahead of time?
You can prepare the vegetable-and-potato base a day ahead, cool it promptly and refrigerate it. Reheat the base until steaming, add the milk and cream, then cook the fish just before serving. This approach helps keep the fish tender and prevents it from breaking down during storage and reheating.

Why did my soup turn grainy or separate?
Dairy can separate when the soup boils hard, and a flour mixture can feel lumpy if stock is poured in too quickly without stirring. Add stock gradually, stir as you pour, and keep the pot at a gentle simmer once the milk and cream are in. If it looks slightly separated, remove it from the heat and stir gently; avoid blending, which would break up the fish.

How can I tell when the fish is cooked?
The flesh should be opaque and flake easily, but color and flaking are not substitutes for a temperature check. Measure the thickest piece with a food thermometer and cook fish to 145°F (63°C), the USDA FSIS safe minimum. Since different pieces may vary in thickness, check a larger piece and remove the pot from the heat promptly once it reaches temperature.

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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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