Peel, wash and halve the potatoes and cook in boiling salted water for about 20 minutes. Wash and clean the radishes and cut into strips. Wash chives, shake dry and cut into small rolls.
Drain the potatoes and press them through a potato ricer or mash them finely. Stir in sour cream, radishes and chives, except for a little bit for garnishing. Season to taste with salt, pepper and caraway.
Clean the salad, wash and shake dry. Cover bread slices with salad leaves and potato cheese and sprinkle with remaining chives and radishes.