Gumbo thickener is a type of stew or soup that is popular in the southern United States. It is usually made with a combination of vegetables, meats, and spices, and is often thickened with either FILE, roux, or OKRA. FILE is a powder made from the dried leaves of the sassafras tree, which is native to the southeastern United States. Roux is a mixture of fat and flour that is cooked together until it forms a paste. OKRA is a vegetable that is native to Africa and is often used as a thickening agent in gumbo. All three of these ingredients are commonly used to thicken gumbo.