Remove the skin from the potatoes, place them on a spoon and, using a long, thin, sharp kitchen knife, score the potatoes four-fifths of the way through, i.e., cut down three-mm-thin slices until the blade touches the spoon. This way the potatoes are not cut all the way through and stay together like a fan.
Preheat the oven to 180 degrees.
Stick one and two rosemary needles and garlic slices, respectively, between each potato slice. Sprinkle with a tiny bit of sea salt and bake in the oven for eighteen minutes.
Turn the heat down to 150 °C and cook for another six minutes.
Or grill on a charcoal grill for fifteen to twenty minutes until crispy.