Peel the skin off the smoked fish fillets and cut the meat into small cubes. Clean, rinse and chop the carrot, celery and leek, blanch separately in salted water and then rinse in iced water. Rinse, dry and chop the dill. Soak the gelatine in cold water.
Heat the fish stock, squeeze out the gelatine and let it melt in the warm stock. Season the stock with salt, sugar and white wine.
Mix fish and vegetable cubes with pink pepper and dill. Place in a baking dish (approx. 500 ml) and fill with the cooled fish stock. Leave the aspic to cool for a few hours.
Remove the horseradish from the peel and grate finely. Mix yogurt, crème fraîche, salt, sugar, juice of one lemon, pepper and horseradish with a blender until creamy.
Turn out the aspic, cut into slices and serve with the horseradish mousse. Serve with fresh frisée salad and baguette.
Tip: Use creamy natural yogurt for an even finer result!