A red rust-coloured sauce that is traditionally made by pounding together red chilli pepper, bell pepper or Tabasco sauce, garlic and cooked potato or fresh breadcrumbs. The mixture is diluted with olive oil and stock from a fish or chicken bouillabaisse soup. Also fish or chicken liver, saffron, lemon juice, basil, tomatoes, thyme or savory can be added to the sauce.

Rouille is usually used to flavour fish stocks and soups.

Mayonnaise rouille is made by seasoning plain or garlic mayonnaise with pureed red bell pepper.