5 tbsp duck fat
16 medium-sized Maris Piper or King Edward potatoes (each about 175g/6oz)
8 garlic cloves
8 sprigs thyme
Preheat the oven to 190C/170C Fan/Gas 5.
Parboil the potatoes in salted water for 7–8 minutes, or until almost cooked (they will still feel firm when pierced with a knife). Drain thoroughly using a colander, then shake the potatoes around a little in the colander until the outsides are roughened. Set aside, uncovered.
Put the duck fat into a roasting tin and heat in the oven for 5 minutes.
Add the drained, roughened potatoes to the tin of hot duck fat, then sprinkle over the garlic cloves, thyme and sea salt and mix until the potatoes are well coated in the fat. Return the tin to the oven and roast for 45–60 minutes, or until golden and crunchy.