Soupe de Poissons Provençale

This soup, popular in Provence and on the island of Corsica, is a good way to use Mediterranean fish that are often full of bones. You will need a variety of small whole fish, both rich species such as smelt and mackerel and white-fleshed ones such as perch, hake, pollock, or whiting. Choose whatever is fresh and inexpensive. Puréeing is best done with a food mill fitted with the coarsest grid, or you can work the soup through a very coarse strainer or fine-mesh colander. (A food processor