Wash the potatoes, cut in half lengthways, pat dry. Mix the olive oil and salt in a bowl, turn the potatoes in it. Spread on a baking sheet lined with baking paper, bake in a preheated oven at 180 degrees for about 30 minutes, sprinkle with sesame seeds and finish cooking in another 15 minutes. If necessary, reduce the heat so that the sesame does not burn.
Mix in the quark, sour cream and the chopped herbs and spring onions. Stir in mineral water. Salt and pepper the herb quark as desired. Serve with the baked sesame potatoes.