8 slices thick-cut white bread
softened butter, for spreading
1kg (2lb 4oz) potatoes (I used Maris Piper)
1 litre vegetable oil, for deep frying
sea salt flakes
tomato ketchup, to serve (optional)
Spread one side of each slice of bread generously with butter.
Line a couple of baking sheets with kitchen paper.
Peel and cut the potatoes into thick finger-sized chips, about 6 x 1.5cm (2¼ x ½in). Place in a bowl of cold water as you go. Drain well. Cook the potatoes in a large pan of boiling, salted water for 5–8 minutes, or until just tender. Drain really well, then spread out on the prepared sheets to thoroughly dry and cool.
Pour the oil into a medium saucepan and heat to 140°C (285°F) – a cooking thermometer will help you achieve an accurate temperature. Cook the potatoes in batches for 6–8 minutes until they start to take on some colour. Remove with a slotted spoon and drain on more kitchen paper while you cook the remaining potatoes.
Increase the temperature of the oil to 190°C (375°F) and cook the chips in batches for a second time for 2–3 minutes, or until golden-brown, crisp on the outside and fluffy in the middle. Remove from the oil with a slotted spoon, drain on kitchen paper, season with salt and serve immediately stuffed between two slices of thickly buttered bread.