First I boil fish broth, in addition to fillets, I use the backbone, offal from the belly and the tail of salmon. I pour cold water over the fish and put it on medium heat. I add half an onion and pepper. I bring it to a boil, be sure to remove the foam formed during cooking.
Celery, carrots, half of the remaining onion and potatoes I cut into cubes about the same size. One potato I leave whole.
In a saucepan I pour vegetable oil, add butter and on a mixture of oils I fry carrots, onions and celery.
I strain the broth. I separate fish meat from skin and bones and put it aside. Boiled onions and peas I remove. I add broth to vegetables, there I move potatoes and cook over low heat for 20 minutes until the potatoes are ready. Then I take out a whole potato, mash it with a fork and send it back to the pot, it will give the broth a thicker and velvety texture.
I add to the broth the put aside fish, bay leaf.
To thicken the soup, I mix flour with cream, pour the mixture into the soup. Salt to taste. I stew soup for 10-15 minutes more. I bring to a boil and turn off, having covered with the lid. I give the dish time to infuse.