Ingredients

Step by step

1. Cut the potatoes into chunky chips, 1-1.5cm across.
2. Pour the oil into a wide, deep pan (the oil should be at least 4cm deep, but the pan must be no more than half full); heat to 140°C. If you don't have a thermometer, estimate the temperature by dropping a small piece of bread into the pan: if it takes 8-10 seconds to crisp, the oil is about 140°C; if it crisps in 3-4 seconds it's about 180°C.
3. Add the chips, in batches, and cook for 8 minutes; the chips should be soft but not coloured. Keep them moving so they don't stick to the pan. Have ready a tray lined with kitchen paper. Remove the chips from the pan with a slotted spoon and drain on the tray. Keep them at room temperature for up to a few hours before you finish them.

4. Meanwhile, make the aioli. Preheat the oven to 170°C, fan 150°C, gas 3. Drizzle the halved bulb of garlic with the olive oil and roast in a small baking tray for 30 minutes at until soft. Cool to room temperature then squeeze the garlic out of the skins. Mash in a bowl and stir in the mayonnaise. Season to taste, adding a little lemon juice if you like.

5. When you are ready to finish cooking, heat the oil to 180°C – when a piece of bread dropped in the oil crisps in 3-4 seconds.
6. Cook the chips in 2 batches, until golden brown and very crisp, about 3-4 minutes. Drain on paper, scatter with your chosen salt and serve at once with the roasted garlic aioli.