Rouille is a rust-colored sauce made with cayenne pepper, garlic and breadcrumbs blended with olive oil and fish stock. Spoon it into the soup to thicken it or spread it on toast and serve separately.

To make your own rouille, sweat one or two crushed garlic cloves in a little olive oil, then add about 1/3 cup of crumbled white bread and 100 ml of the fish soup and reduce it all to a thick smooth pulp. Using a balloon whisk, beat in 100 ml of olive oil a little at a time, and season with salt, pepper and cayenne.