Put the maties in a bowl and pour mineral water over them until the fish is completely covered. Soak for about 2 hours. In the meantime peel and finely dice the onion. Roughly dice rolls and soak in cold water
Peel the potatoes, wash them thoroughly and halve them depending on size. Remove the maties from the water, rinse again with cold water. Dab dry with kitchen paper. Finely dice the maties, place them in a tall mixing bowl and puree them finely
Squeeze the buns well. Knead the maties, minced meat, bread roll, onion and egg to a smooth mixture. Season with pepper and very little salt. Form 8-10 meatballs from the mixture with moistened hands
Cook the potatoes in boiling salted water for about 20 minutes. Put the meatballs in approx. 3 litres of boiling water and let them simmer at low to medium heat for approx. 15 minutes (until they rise to the top.) Lift them out of the cooking water and put them aside. For the sauce, measure 750 ml of cooking water from the meatballs
In the meantime, wash the dill for the salad, shake dry and cut finely. Mix lemon juice, sour cream, 3 tbsp. sugar and dill. Season to taste with salt and pepper. Wash the salad, drain well and pluck into bite-sized pieces. Put the salad in a bowl and pour the dill-cream dressing over it
Melt the fat in a saucepan, dust with flour, sauté and gradually add the measured cooking water while stirring. Bring to the boil, season to taste with salt, pepper and sugar. Simmer for 2-3 minutes, stirring several times. Mix the sour cream and egg yolks in a small bowl. Stir in 4-5 tablespoons of the hot sauce drop by drop. Then stir into the sauce. Add the capers. Place meatballs in the sauce, heat briefly but do not boil. In the meantime wash parsley, shake dry and chop finely
Drain the potatoes, sprinkle with parsley and toss briefly. Arrange meatballs with sauce and parsley potatoes on plates. Add salad
waiting time approx. 1 3/4 hours