Crispy Fish and Chips with Mushy Peas

Cut the potatoes into chips about 1.5cm thick. Rinse under cold water

Simmer in salted water for 6-8 minutes until just tender at the edges but not breaking.

Drain carefully

Cool on a rack for at least 15 minutes.

Heat the oven to 120°C fan and put a wire rack over a baking tray for holding cooked food. Heat the frying oil to 150°C. Never fill a saucepan more than halfway with oil and never leave it unattended.

Fry the chips in 3-4 batches for 5-6 minutes each until cooked through but pale. Drain on a rack. Raise the oil to 190°C.

Pat the fish completely dry and season with 1/2 tsp salt. Put the 50g flour on a plate. In a bowl, whisk 120g flour, cornflour and baking powder, then whisk in the cold lager and vinegar only until combined; a few small lumps are fine. Keep the fish and batter refrigerated until the final frying stage.

Put the peas, butter and water in a saucepan and cover.

Cook the covered peas for 4 minutes. Keep covered briefly until the finishing step.

Lightly crush the peas with a masher, leaving texture. Add mint, lemon, salt and pepper, then cover to keep warm.

Return the chips to the 190°C oil in small batches for 2–4 minutes each until crisp and golden. Drain and season immediately. Keep each finished batch uncovered on the warm rack in the 120°C fan oven while you fry the fish.

Dust two fish fillets with flour, shake off the excess, dip in batter and let the excess drip away. Lower them carefully into the 190°C oil away from you. Fry for 5-7 minutes, depending on thickness, until crisp and the centre reaches at least 63°C. Drain on the warm rack and repeat.

Serve the fish immediately with chips, mushy peas, lemon, vinegar and tartare sauce. Allow used oil to cool completely before straining or disposing of it; never pour it down the sink.