1. Preheat the oven to 200°C/400°F/Gas 6.
2. Cook the potatoes in a pan of lightly salted, boiling water for 5 minutes then drain well. Return to the pan with the garlic slices, sliced onion, salt flakes and olive oil. Then cover the pan with a tight-fitting lid and shake the pan vigorously.
3. Arrange onto a non-stick baking tray in an even layer and roast for 30 minutes, until golden and crispy, turning once with a spatula halfway through the cooking time.
