To quote the regional cookbook Louisiana Entertains, “Good gumbos are like good sunsets: no two are exactly alike, and their delight lies in their variety.” All gumbos use a roux. However, in addition to a roux, some gumbos flavor and thicken with okra and others call for filé powder. Integral to Creole and Cajun cooking, filé powder is made from the dried leaves of the sassafras tree. It is used not only to thicken gumbo but also to impart its mild, lemon flavor. Filé powder should be stirred into gumbo toward the end of cooking or it will become tough and stringy.