Wash the potatoes and cook in boiling salted water for about 40 minutes. In the meantime, crush or very finely crumble toast bread with the universal kitchen machine. Mix sour cream, egg yolk, cheese and toast.
Season with cayenne pepper. Cut the potatoes in half lengthwise. Hollow out a little and add to the cream mixture. Fill the mixture into the potato halves in portions. Place bacon on top. Bake under the hot grill until golden brown.
For the vinaigrette season vinegar with salt and pepper. Whip the oil under it and add cranberries. Wash the salad, pluck into bite-sized pieces and arrange on plates. Pour the vinaigrette over the salad.
Serve with the potatoes au gratin.