Wash potatoes thoroughly and cook in boiling water for about 20 minutes. Take them out and wrap them in aluminium foil. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 45 minutes.
For the sour cream, mix sour cream and quark. Press garlic cloves through a garlic press, cut chives into small rolls and stir both into the cream. Season with salt and pepper.
Take the potatoes out of the oven, cut them crosswise, press them slightly apart and add 2-3 tablespoons of sour cream.