Rouille

This thick French sauce is usually used as a garnish for fish and fish soup dishes, most notably in the famous traditional Provençal fish stew known as bouillabaisse. It consists of garlic, saffron, chili peppers, olive oil, breadcrumbs, and sometimes egg yolks, because some recipes use mayonnaise as a base.

The name of the sauce translates as rust due to the intense, reddish-brown color of the sauce. Although the origins of rouille are difficult to pinpoint, since modern bouillabaisse is always served with rouille, it can be deduced that the sauce must have coexisted with the dish since the late 18th century, when the first recipe for bouillabaisse appeared in print.