Good old fish and chips is the ultimate British street food, ideally eaten by the seaside on a blustery day! Triple-cooked chips are a bit of an effort, but they are worth it – the chilling in the fridge guarantees a supreme crunch. And if you are making chips, you may as well make plenty, so this recipe gives a generous portion each.
Peel the potatoes and slice into 1cm-thick chips. Place in a colander and rinse well under cold running water. Tip into a large saucepan and shake in a little sea salt. Pour in enough boiling water to submerge the chips and cover with a lid. Bring back to the boil and cook until just tender when pierced with the tip of a sharp knife, about 3–4 minutes. Drain well and spread out on a large baking tray to steam dry. Leave to go completely cold.
Heat the oil in a deep fat fryer to 120°C/250°F. Fry the parboiled chips for about 5 minutes until soft all the way through but not coloured at all. You may need to do this in 2 or 3 batches depending on the size of your fryer. Drain thoroughly then spread out once again on a baking tray in a single layer. Leave to go cold then chill in the fridge for a few hours, or preferably overnight.
Make the tartare sauce by placing the egg yolks, mustard and salt in the bowl of a food mixer. Using the whisk attachment, whizz until smooth and completely combined. Measure the oils into a jug, then, with the motor running, start to add the oils very slowly, literally drop by drop at first, letting the sauce whizz and mix between each addition. If you go too fast you risk separation rather than emulsification. Once the egg is thickening and turning paler you can increase the flow of oil to a few drops at a time, very gradually increasing to a thin trickle as it begins to look like mayonnaise. When all the oil is in, add the lemon juice and whisk once more until combined. Then fold through the cornichons, parsley, capers and shallot with a tablespoon. Taste to check the seasoning, adding black pepper, extra salt or a squeeze more lemon to taste before scooping into a bowl and chilling until needed (overnight is fine).
For the batter, mix the plain flour, cornflour, turmeric and salt together in a large bowl. Cut the fish into 4 even-sized pieces and lay on a large plate or baking tray. Take a generous tablespoon of the seasoned flour and sprinkle it over the fish, then toss the fish around to get a light, even coating. Gradually pour the beer into the remaining flour in the bowl, whisking all the time until you have a smooth batter.
Preheat the oven to 140°C/120°C Fan/Gas Mark 1 so you can keep the fish warm while the chips are cooking. Heat the oil in the deep fat fryer to 180°C/350°F.
Have the plate of fish and bowl of batter right next to the deep fat fryer. Dip a piece of fish into the batter, completely submerging it so it gets an even coating, then immediately slide it gently into the hot oil. Repeat with another piece of fish and leave both to fry for about 5 minutes, until the batter is golden and puffed up. Drain briefly over kitchen paper and slide into the warm oven on a baking tray while you repeat with the remaining 2 pieces. Slide those into the oven too, to keep warm while you give the chips their final crisping in the fryer.
Fry the chips for a second time – at the higher heat of 180°C/350°F – again in batches if necessary, until golden and really crisp, about 4 minutes. Drain briefly before scattering over a little sea salt and serving immediately with the fish and the tartare sauce with lemon wedges on the side.