Peel the potatoes and cut into 1cm-thick chips. Parboil the chips in boiling salted water for 8 to 10 minutes, or until soft but keeping their shape. Drain in a colander and leave to steam until completely dry – this is very important before frying.
Heat a deep-fryer to 180ºC or fill a deep saucepan to three-quarters full with vegetable oil over a high heat. For safety, clear the kitchen and never leave hot oil unattended. To test when the oil has reached the required temperature, drop in a cube of bread – at 180ºC it will turn golden in 10 seconds. Carefully fry the chips, in batches, until golden crisp. Drain on kitchen towel then sprinkle with sea salt.
If you’re feeling funky, peel and thinly slice the garlic and pick and finely chop the parsley and carefully mix with the hot chips. Or if you're in a posh mood, drizzle them lightly with truffle oil (combine with olive oil if it’s very strong) and finely grate over the Parmesan. Serve nice and hot.