Roast nut flakes in a pan without fat until golden brown, let them cool down. Wash, clean and slice the tomato. Clean and wash spring onion and cut into rings. Cut the fillet into small pieces.
Mix quark with horseradish, season with salt and pepper. Spread bread with quark. Spread tomatoes, trout fillet and spring onions on it. Sprinkle with nut leaves and season with pepper.