Sprinkle the fillets with salt/sugar and refrigerate for at least 1 hour. Place the fillets in an ovenproof dish and add a small glass of white wine. Bake in the oven at 150 degrees Celsius (302 degrees Fahrenheit) for about 5-7 minutes until the fish is warm in the center (check with a meat needle if necessary). Drizzle with lemon juice.

Cut the carrots into small cubes and the onion into thin rings. Cook them al dente in 1/2 dl of stock.

 

Rinse the bones and remove the blood from the carcass.. Put everything in a pot and add water as needed to cover.  It is best to use as little water as possible since it will be reduced later (i.e., some of the water will evaporate). Bring to a boil and start skimming the foam that forms on the surface (protein with impurities).

Let it simmer for 20 minutes and turn off the heat. Let it stand for another 10 minutes before straining. Reduce to about 1/3 so it's ready to be used or frozen for another good occasion.   

Use the same amount of cream as you have fish stock left and reduce further. Season with salt/pepper.

 

Place onion/carrot in a warm deep plate and the fish on top. Add sauce on top and sprinkle with chopped chives.