Peel and finely dice the shallot. Wash the fish, dab dry and chop finely. Wash parsley, shake dry and chop finely. Heat butter in a small pan and fry shallots until translucent.
Mix in the parsley.
Remove from the stove and let it cool down a little. In the meantime, wash the shrimps and pat them dry with kitchen paper. Chop the prawns finely. Mix prawns, trout, shallots and butter mixture, breadcrumbs and egg yolk well.
Season with salt and pepper.
Form 4 meatballs from the mixture with moistened hands. Heat the oil in a coated pan and fry the meatballs on each side over medium heat for 4-5 minutes.
In the meantime, wash the chives, shake them dry and cut them into fine rolls. Put some rolls aside for garnishing. Mix crème fraîche, milk and mustard until smooth. Add the chives and season with salt, pepper and sugar.
Arrange the meatballs with some dip, sprinkle with chives. Add the remaining dip in a glass.