Wash the potatoes thoroughly and cut them in half lengthwise. Wash the rosemary, dab dry and, except for a twig, pluck the needles from the twigs and chop. Line a baking tray with baking paper, sprinkle with salt and rosemary. Place the potatoes on the baking tray with the cut surface facing down. Sprinkle with olive oil.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes. Turn the potatoes halfway through the cooking time. Remove and arrange. Garnish with rosemary