Wash the potatoes, cut in half lengthwise and place on a baking tray with the cut surface facing upwards. Cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 50 minutes. In the meantime, wash, clean, quarter and seed the tomatoes. Cut the fruit flesh into small cubes. Wash and clean the cucumber and cut it into small cubes. Clean, wash and finely chop the radishes.
Wash chives and cut into small rolls. Cut the cress briefly. Mix quark and prepared ingredients. Season to taste with salt and pepper. Allow the curd to stand and season to taste again just before serving, seasoning if necessary. Arrange potato halves on salad and parsley leaves and serve with the quark