8 small鈥搈edium potatoes, each one approx. 75g/2戮oz, scrubbed (ideally, all-rounders or floury potatoes)
陆 tsp dried thyme, rosemary or mixed herbs
陆 tsp coarsely ground black pepper
3 tbsp sunflower, vegetable or olive oil, plus extra for greasing
陆 tsp flaked sea salt
small knob of butter, approx. 15g/陆oz (optional)