Wash the potatoes thoroughly, wrap them in aluminium foil and place them on a baking tray. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 1 hour. In the meantime, pierce the eggs and boil them hard in boiling water for 10 minutes.
Quench the eggs under cold water and let them cool down. Clean and wash the radishes and cut them into fine sticks. Wash the herbs and dab dry well. Cut the chives into fine rolls, remove the leaves of the other herbs, except for some for garnishing, from the stems and chop finely.
Peel the eggs and cut 1 egg into slices. Put 2 slices aside for garnishing and chop the rest of the egg. Mix the quark with the milk until creamy and season with salt and pepper. Put some chopped egg, herbs and radishes aside and stir the rest into the quark.
Season again with salt and pepper. Remove the potatoes from the foil and cut them crosswise. Press the potatoes apart and put them on a plate. Spread some quark in the potatoes and put the rest in a bowl.
Sprinkle quark with the remaining radishes, egg and herbs. Serve immediately garnished with egg slices and herbs.