To begin, melt the butter in a large pot over medium heat. Add the chopped onion and sliced leek. Sauté gently for 5–7 minutes, stirring occasionally, until the vegetables are soft but not browned. This forms a subtle aromatic base.

Add the carrot slices and diced potatoes to the pot. Stir them into the leeks and onion for 1–2 minutes to coat them with the buttery mixture, allowing the flavours to mingle before adding liquid.

Pour in the fish stock, ensuring the vegetables are fully covered. Raise the heat to bring the mixture to a gentle boil, then reduce to a simmer. Cover partially and cook for about 15 minutes, or until the potatoes are just fork tender.

Once the vegetables are cooked, season the soup with salt and white pepper. Taste the broth at this point, adjust seasoning carefully, as salmon and cream will mellow it later.

Gently add the salmon cubes to the simmering soup. Lower the heat slightly and let the fish cook through for 5–6 minutes. Avoid stirring vigorously to keep the tender fish pieces intact.

Pour in the double cream, stirring gently to combine. Do not boil after adding cream, keep the heat low and allow the soup to warm through for another 3–4 minutes. This step gives the soup its signature creamy body.

Add the chopped dill just before turning off the heat. Fresh dill is key, avoid dried substitutes. It brings a clean, herbal brightness that balances the richness of the soup.

Let the soup sit covered for 2–3 minutes off the heat before serving. This short rest allows the flavours to deepen and meld into the broth. Meanwhile, warm some rye bread for serving.

Serve hot in wide bowls, topped with a few extra sprigs of dill if desired. Pair with thick slices of buttered rye bread for a complete Finnish experience. The soup should be creamy but not heavy, light, silky, and deeply comforting.