Clean the soup vegetables and cut into fine strips. Blanch in boiling water for approx. 2 minutes and then rinse in cold water. Cut the lemon into thin slices.
Spread out 4 pieces of aluminum foil (each large enough to wrap the fish with) and spread the vegetables on top. Place the fish fillets on top, season with salt and pepper and place the lemon wedges on top. Fold up the aluminum foil over the fish and seal it tightly - it should be really tight.
Bake in a preheated oven at 200 ° C for approx. 20 to 25 minutes.
During this time, leave the butter out in a saucepan and add the flour. Let it boil briefly and deglaze with the cream. Then add the vegetable stock, salt and pepper. Finally, clean the dill, cut it finely and add it. If you like it a bit sour, you can now add a little lemon juice.
Arrange the fish with the vegetables on plates and pour some of the sauce over them.