1. Preheat the oven to 200˚C/gas 6.
2. Make small vertical slits approximately 2mm apart in each potato, taking care not to cut right through to the base.
3. Place the potatoes in a large roasting tin, then generously brush with the oil, sprinkle with the salt and scatter over fresh thyme.
4. Roast for 40 minutes until the potatoes are crispy and golden brown.