THIS SOUP, served with a green salad, rosé wine, and a fruit tart for dessert, makes a wonderful lunch or light supper. It is also the base for the American Bouillabaisse. Most traditional recipes for this soup call for fish fillets to be cooked as part of the soup base and discarded. With today’s fish prices, I find this wasteful and extravagant. In my Soupe de Poisson, I poach the diced fillets in the soup at the last minute and serve them with the soup. For an even heartier version I add scallops and/or shrimp, poaching them at the same time as the fish.