For the salad, cook the potatoes for about 20 minutes. Cut the cucumbers into slices. Peel and finely dice onions. Quench potatoes, peel and let cool down a little. Boil 100 ml water, broth, vinegar, pepper, some sugar and 2⁄3 onions.
Stir in the cucumber stock, 2 tsp. mustard and oil. Season to taste.
Cut the lukewarm potatoes into slices. Mix with hot marinade and cucumber. Peel, core and chop apple. Let the salad steep for at least 2 hours.
Soak the rolls for the meatballs. Wash and chop the parsley. Knead with minced meat, squeezed out roll, rest onions, egg and 2 teaspoons mustard. Season with salt, pepper and paprika.
Cut the cheese into 8 cubes. Shape the minced meat into 8 meatballs, pressing 1 cheese cube each into the middle. Fry in 2 tablespoons of hot lard on each side for 7-8 minutes. Wash the chives and cut into small rolls.
Stir into the potato salad, season to taste.