Rouille

Rouille is a sauce that can be thickened with bread crumbs or crusts from old bread. It traditionally used as a garnish with the fish and shellfish soup, bouillabaisse, both to add taste and to thicken the soup. It is often made by pureeing together olive oil, red chile peppers or cayenne, garlic, and saffron, and then thickening with bread crumbs. According to other recipes, it is a form of aioli to which softened old bread, garlic, and cayenne are added.