For the apple stock, wash the dill and cut the flags roughly. Peel and grate horseradish. Wash apples, quarter them, remove seeds and dice very finely. Mix apples, horseradish, dill, apple juice and oil. Season with salt and pepper.
Peel and wash the carrots and cut them into very fine sticks. Clean and wash spring onions and cut them into fine strips. Rinse fish and cut into 4 pieces. Season with salt and pepper.
Arrange carrots, spring onions, fish and apple stock in 4 packets of double-layered aluminium foil. Close the packs and cook on the preheated grill for about 15 minutes.