What is roux Published on Jul 17, 2020 Updated on Jul 28, 2020 in « Back to Glossary IndexA roux is a mixture of equal parts flour to fat by weight. The fat is traditionally butter, and the flour is typically AP (all purpose) flour. Used to thicken soups, stews and gravy.Related Articles:Glossary: béchamelGlossary: cornstarchGlossary: slurryUltimate Vegan LasagnaThe best lasagna you will ever have! Topped off with a creamy dairy free bechamel sauce. It's also 100% VEGAN lasagna.