Wash potatoes thoroughly and cook in boiling water for about 25 minutes. Drain, rinse and peel. Cut potatoes into slices. Peel onions and dice very finely. Heat 5-6 tablespoons of oil in a small pan, add half of the onions and fry over low to medium heat until translucent.
Sprinkle with sugar, season with salt and pepper. Deglaze with stock and vinegar, bring to the boil and simmer for 2-3 minutes. Pour over the still warm potatoes, mix and leave to stand for about 1 1/2 hours.
Soak rolls in cold water. Drain meat on kitchen paper, cut very finely and then chop very finely with 2 large, heavy knives (minced meat type). Squeeze the bread roll well.
Place the meat, remaining onions, bread roll, egg, mustard, 1 teaspoon salt, 1 teaspoon pepper, pimento and cloves in a bowl and knead well.
Form 8 flat meatballs from the mixture. Heat 3 tablespoons of oil in a large frying pan and fry the meatballs on each side for 6-8 minutes at medium heat. Wash the chives, shake dry and cut into fine rolls.
Mix the chives into the potato salad.
Season potato salad again with salt, pepper and sugar. Arrange potato salad and 2 meatballs on plates. Garnish with chives as desired.