Place fish bones and head, onions, black pepper and Bay leaf in a saucepan, cover with cold water and put on medium heat. Bring contents of saucepan to a boil, reduce heat and, periodically removing the foam – the more the better – cook for 25 minutes. Strain the broth and pour it back into the pan, adding the diced carrots and potatoes and thinly sliced leeks. Boil 20 minutes until tender potatoes and add the trout fillet, cut into the same cubes. Increase the heat, bring the soup to a boil, pour in the sour cream, add finely chopped dill, season with salt and pepper. Remove the soup from the heat, cover and let steep for five minutes. Serve, adding a little more dill.

P. S. I took the products 2 times more, because preparing for 4л.