Marmitako recipe: the Basque albacore stew from the boats

This marmitako recipe follows the Basque fishermen's stew as it was cooked on board: albacore, potatoes and peppers in one pot. The technical key is that the tuna never boils: it goes in off the heat and cooks in the residual warmth of the broth, which keeps a lean fish juicy.

The name comes from the marmita, the lidded pot on the boats that chased albacore, bonito del norte in Spanish, across the Bay of Biscay. This year's costera has run long: Gipuzkoa's inshore fleet had landed 6.87 million kilos by 21 August, against 6.22 million a year earlier, and the Basque Government has said the season could last into mid-October, according to figures compiled by Geogastronómica.

Ingredients

Marmitako is judged by the tuna, and the tuna is ruined the moment the pot boils.

• 500 g fresh albacore (bonito del norte) loin, skinned, in 3 cm cubes
• 1 kg all-purpose potatoes, such as Kennebec or Spunta
• 2 dried choricero peppers
• 1 large onion, finely chopped
• 2 green Italian frying peppers, chopped
• 2 garlic cloves, thinly sliced
• 80 ml extra virgin olive oil
• About 1 litre cold water
• Fine sea salt
• 2 tbsp chopped flat-leaf parsley

Method

1. Soak the choricero peppers in hot water for 30 minutes, split them and scrape the flesh from the skins. The flesh gives colour and sweetness; the skin stays tough and bitter.
2. Salt the tuna cubes lightly and refrigerate them until the end, so the seasoning reaches the centre.
3. Sweat the onion, green peppers and garlic in the oil in a wide casserole over medium-low heat for 15 minutes, without colour. Browned onion makes the broth muddy and bitter.
4. Stir in the choricero flesh for 2 minutes, so the oil takes up its colour.
5. Peel the potatoes and break them into rough 4 cm pieces: push the knife in halfway and snap each piece off. Torn surfaces release more starch than clean cuts and thicken the broth without flour.
6. Turn the potatoes in the sofrito for 2 minutes, cover with water and salt. Bring to the boil, then simmer gently for 20 to 25 minutes, until the edges crumble. A hard boil breaks them before the centres cook.
7. Crush two or three pieces against the side of the pot if the broth needs more body.
8. Take the pot off the heat, add the tuna, push it under the liquid, cover and rest for 5 minutes. Boiling tightens lean albacore into dry fibres; the hot broth cooks it gently and keeps it moist. Finish with parsley and serve from the pot.

Tomato or no tomato, and what to pour

Basque cooks argue about tomato. Some grate a ripe one in with the peppers; others leave it out, because its acidity firms the surface of the potato and slows the thickening. Out of season, a thick piece of salmon takes the same off-heat method.

Pour a cold txakoli from Getaria, whose sharp acidity cuts the oil, and plan the trip with our guide to what to eat in San Sebastian.