Make a fish stock with the whiting, sole bones, onion, carrot, thyme, half a bay leaf, 8 cups of water, salt and pepper. Simmer for 20 minutes. Strain. In a large saucepan melt half the butter. Whisk in the flour and cook for 1-2 mintues. Stir in the fish stock, mushrooms and several parsley sprigs. Simmer 12-15 minutes, skimming occasionally. Open the oysters and pour their liquid into a small bowl. In a medium saucepan melt 2 tablespoons of the remaining butter. Add the white wine and boil for 4 minutes. Reduce heat to a simmer. Add the reserved oyster liquid and the oysters. Simmer for 3 minutes. Remove the oysters with a slotted spoon and set aside. Pour their cooking liquid into the soup. In a small bowl whisk together the egg yolks, and crÅme fraöche. Stir the yolk mixture into the soup but do not boil. To serve, place the oysters in soup bowls and ladle in the soup. As an alternative, place the oysters on skewers, sprinkle them with Cayenne pepper, dip in egg and then bread crumbs. Cook in hot oil and butter until golden.
