For the dough, mix the eggs with the flour, mineral water and milk to a smooth dough. Pepper and salt, then let rest for 10 minutes. Wash the herbs, pat dry with a crepe and chop finely, then mix with the batter.
Heat the butter in portions in a large, non-stick pan, bake 4 pancakes and then keep them warm.
For the cream, beat the cream cheese with the horseradish, creme fraiche and lemon juice in a bowl until frothy. Season to taste with salt / pepper, cayenne pepper and sugar.
Brush the pancakes with the cream, place 1 trout fillet on each and roll up the pancakes. Serve lukewarm.