Cook the potatoes in boiling salted water.
Finely chop the spring onion and chives.
In a large bowl, mix together the quark, yoghurt, chopped chives and spring onions (reserve some for garnishing).
Season with some sea salt and freshly ground black pepper, then set aside in the fridge.
When the potatoes are cooked, remove from the pan and allow to cool enough to handle - you can run them under cold water to speed this up a bit.
Cut the potatoes in half or quarters, depending on size, then mix them in with the quark mixture.