Fish Soup with Aïoli and sauce ardente

This soup, originally from the Ermitage Restaurant in Les Angles, near Avignon, is a wonderful cross between a bouillabaisse and a bourride. It is a superb pièce-de-résistance, a golden, creamy broth, enriched with aïoli and chunks of fish. The original contained eels, which are in plentiful supply in the lagoons of Languedoc. Add them, if you like the rich taste of eel.