Leek and Potato Soup with Smoked Mackerel

A smooth leek and potato soup makes a simple, comforting base: mild alliums, buttery softness and potatoes blended into a velvety bowlful. Here it takes on a distinctly savoury, smoky edge from flaked smoked mackerel, added at the end so the fish stays tender rather than drying out. Crème fraîche rounds the soup without making it heavy, while bay leaves give the stock a quiet aromatic depth. It is an easy dinner soup with enough richness to feel substantial, especially served hot with extra black pepper and the remaining mackerel scattered over the top.
Recipe by JustRecipes Editorial Team
Content validated: August 2026 How we create recipes
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Cuisine style Dutch-inspired comfort food
Cooking style One-pot cooking • Minimal cleanup
Time commitment Under 1 hour

Why this recipe works

  • Velvety body: Yukon Gold potatoes blend smoothly into the stock, giving the soup natural thickness without needing heavy cream.
  • Gentle depth: Softened leeks, bay leaves, butter and crème fraîche build a mellow base that lets the smoked mackerel stand out.
  • Straightforward timing: The soup comes together in one pot, with the fish added only at the end so it stays moist and distinct.

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Ingredient notes

  • Clean the leeks well: Slice the leeks lengthways and rinse between the layers, as grit often sits close to the root end.
  • Use smoked mackerel gently: Most smoked mackerel is already cooked, so fold it in just before serving rather than simmering it.
  • Crème fraîche adds stability: Crème fraîche gives the soup a rounded finish and is less likely to split than lower-fat dairy when warmed gently.

Texture tips

  • For a silkier soup: Blend thoroughly, then let the soup stand briefly so trapped air bubbles settle before serving.
  • Avoid boiling after dairy: Once the crème fraîche is added, keep the soup over a low heat to preserve the smooth texture.
  • Keep the fish moist: Add the mackerel at the end so the flakes stay juicy rather than becoming dry or tight.

Make-ahead tips

  • Make the base ahead: The leek and potato base can be cooked and blended in advance, then finished with crème fraîche and mackerel when reheating.
  • Hold back the mackerel: For the best texture, store the smoked mackerel separately and stir it through just before serving.
  • Reheat gently: Warm the soup in a saucepan over a low heat, stirring often, until piping hot throughout.

Ingredient swaps

  • Lighter dairy option: Greek yoghurt can replace crème fraîche for a lighter finish; add it off the heat to reduce the chance of splitting.
  • Milder smoked fish: Smoked salmon gives a softer texture and gentler smoky flavour if mackerel feels too assertive.

Equipment you'll need

Immersion blender Large pot
Ingredients
Instructions
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  1. Trim the leeks, slice lengthways, then rinse well to remove any grit. Slice the leeks into thin half-moons. Peel the potatoes and cut into small, even chunks.
  2. Melt the butter in a large pot over a medium heat. Add the leeks and cook for 8 to 10 minutes, stirring often, until softened but not browned.
  3. Add the potatoes, bay leaves and vegetable stock. Bring to the boil, then reduce to a gentle simmer and cook for 15 to 18 minutes, until the potatoes are very tender.
  4. Remove and discard the bay leaves. Blend the soup until smooth, then return to a low heat. Stir in the crème fraîche and warm gently for 2 to 3 minutes without boiling.
  5. Flake the smoked mackerel into bite-sized pieces and stir most of it through the soup. Season with black pepper, then ladle into bowls and top with the remaining mackerel.

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Recipe notes

Tips

  • If your smoked mackerel is already cooked (as most is), add it right at the end so it stays juicy and does not dry out.
  • For a silkier texture, blend for a full minute, then let the soup sit for 2 minutes so any bubbles rise before serving.
  • If serving to anyone who is pregnant, elderly, or immunocompromised, ensure the soup is piping hot throughout before serving.

Substitutions

  • Replace Crème fraiche with Greek yogurt for a lighter finish; add it off the heat to prevent splitting.
  • Replace Smoked mackerel with Smoked salmon for a milder smoky flavour and softer flakes.

Storage

  • Refrigerate up to 2 days
  • Cool quickly, then refrigerate in a sealed container. Reheat gently in a saucepan over a low heat until piping hot, stirring often; avoid boiling once the Crème fraiche is in to keep the texture smooth.

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Recipe overview

  • Servings: 3 bowls
  • Total time: 45min (20min active)
  • Difficulty: Easy
  • Cuisine: Dutch
  • Allergens:
    Fish Milk
Beginner friendly One pot Kid friendly
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Equipment you'll need

Immersion blender Large pot

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Black pepper

1 cup ≈ 110.4 g
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Butter

10 oz ≈ 283 g
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Vegetable stock

1 cup ≈ 240 ml
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