Cut slices about 3mm in thickness right across the potato, but keep them attached at the bottom.
If that all sounds a bit too much, there is a quick trick you can use: place the potatoes on a wooden spoon and slice down: the dip in the spoon will prevent you from slicing all the way through.
When you’re finished, place all the potatoes sliced side up in a roasting tray and brush each one with the melted butter and give a good sprinkling of coarse sea salt. Then sprinkle the herbs over the top.
Roast at 200°C/400°F/Gas Mark 6 for approximately 45 minutes or until the slices of the potatoes fan out and turn golden brown.