Rouille (pronounced as /fr/; Occitan (post 1500);: label=[[Provençal dialect|Provençal]]|rolha||rust) is a sauce that consists of egg yolk and olive oil with breadcrumbs, garlic, saffron and cayenne pepper.[1] It is served as a garnish with fish and fish soup, notably bouillabaisse. Rouille is most often used in the cuisine of Provence.