Wash potatoes thoroughly, dab dry and cut into slices. Roll the slices in sesame seeds. Clean and wash spring onions, dab dry and cut into rings. Mix quark, yoghurt and sour cream, fold in spring onions.
Season to taste with salt and pepper.
Heat the oil in a saucepan, fry the potato wedges in portions. Lift them out, let them drip off on kitchen paper and sprinkle with salt. Arrange potatoes on plates, add sour cream.