Plokkfiskur

Ingredients

• 600g cod or haddock fillet, skinned
• 700g floury potatoes
• 1 large onion
• 50g butter, plus more for the dish
• 40g plain flour
• 500ml whole milk
• 1 bay leaf
• 1 tsp salt
• White pepper
• 1 tsp English mustard (optional)
• Icelandic rugbraud or dark rye bread, to serve

Before you cook

• Peel the potatoes and cut them into even 4cm pieces.
• Peel the onion and chop it finely.
• Check the fish for bones and cut it into large pieces that will fit your pan.
• Butter a shallow ovenproof dish.

Steps

1. Boil the potatoes in salted water for 18 minutes until completely tender, then drain them well.
2. Put the fish in a wide pan, pour over just enough water to cover it and add the bay leaf and a good pinch of salt.
3. Bring the water to a bare tremble, then take the pan off the heat and leave the fish to sit for 6 minutes until it flakes.
4. Lift the fish out with a slotted spoon and let it drain on a plate.
5. Melt the butter in a large saucepan over medium heat and cook the chopped onion for 6 minutes until soft and sweet.
6. Stir in the flour and cook for 2 minutes, stirring the whole time.
7. Add the milk gradually, whisking smooth between each addition, until you have a thick, glossy sauce.
8. Simmer the sauce for 4 minutes, then season it with salt, white pepper and the mustard if you are using it.
9. Break the drained potatoes into the sauce with a fork, leaving them chunky rather than smooth.
10. Flake the fish in large pieces into the pan and fold everything together with two or three gentle turns so the fish stays in flakes.
11. Taste and adjust the salt and pepper.
12. Scrape the mixture into the buttered dish and rough up the surface with a fork.
13. Grill on a high setting for 6 to 8 minutes until the peaks are deep gold.
14. Serve straight from the dish with thin slices of buttered dark rye.