Boil water in a suitable container. Add round carrot slices, shredded celery, finely chopped onions, bay leaf, black pepper and salt. Once the marinade comes to a boil, place the fish to boil for 15-20 minutes. To prepare the sauce, beat the yolks in a round-bottomed dish and put them in a water bath over low heat.
Pour in the fish broth and once the mixture becomes a creamy paste, remove from the fire. Trickle the melted butter in. Salt the sauce and add the lemon juice. Then place the boiled fish in a suitable platter, top with the sauce, arrange slices of lemon on it.