Wash the rosemary, shake dry and pluck the needles from the twigs. Wash the potatoes thoroughly and cut them in half lengthwise. Brush a baking tray with olive oil. Sprinkle rosemary on it and place the potatoes with the cut surface on top. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 40-45 minutes
Soak rolls in water. Peel and finely chop the onion. Knead minced meat, onion, egg, mustard, parsley, salt, pepper and squeezed bread roll well. Form about 20 meatballs with moistened hands. Heat the oil in a large pan and fry the meatballs for 8-10 minutes, turning them over.
For the dip, crumble the feta finely and mix with mayonnaise. Stir in yoghurt. Stir in the spice mixture. Season to taste with salt and pepper if necessary
Remove the meatballs from the pan. Remove the potatoes from the oven, turn them on the baking tray and sprinkle the cut surface with coarse salt. Skewer 1 potato half and 1 meatball each with a blob of dip. Arrange on plates garnished with basil leaves