Rinse fish cold, dab dry and cut into pieces. Cover and freeze for about 20 minutes. Clean and wash spring onion and cut into thin rings. Clean, wash and very finely dice the bell peppers.
For the dip, wash the chives and cut into fine rolls. Stir into the yoghurt. Season to taste with salt and pepper.
Finely chop the fish cubes in portions in the universal chopper. Knead fish, egg, spring onion, paprika, breadcrumbs and lemon juice well. Season with salt and pepper. Form approx. 16 small meatballs from the mixture.
Fry the meatballs in portions in 2-3 tablespoons of hot oil over medium heat for 3-4 minutes on each side. Keep the meatballs warm in the oven (at 50 °C).
Peel onion and cut into fine rings. Clean and wash the cress and drain well. Mix vinegar, salt, pepper and 1 pinch of sugar. Fold in 3-4 tablespoons of oil. Mix onion rings, watercress and vinaigrette.
Arrange meatballs, yoghurt sauce and salad.