How to make
Wash the heads and salmon from the ragout and put to boil in enough water to cover them, along with a little salt. Sauté the finely chopped onion and carrot in the butter, with the finely chopped dill and parsley. Once boiling, remove the salmon and debone them.
To the boiling broth, add the stewed vegetables, leave them to boil until ready. When ready, return the meat of the salmon back to the broth and add the milk. Boil for about 5 minutes, then add the cream. Boil for 2 more minutes and thicken with the starch that you've beaten with a little water and the yolk.
Add the lemon juice and boil another minute. Season with salt and lots of black pepper.