Filé Powder

Filé powder or gumbo filé is a herbal powder made from dried and ground leaves of the Sassafras albidum, commonly known as the sassafras tree. These powdered leaves were originally used by Choctaw Indians, but they soon started to be used by the Cajuns in Louisiana, who added it to stews, gumbos, and soups as an earthy thickener and flavoring.

Filé powder should be added to gumbo just before serving, when it's off the heat, because otherwise it can become stringy and too thick. Interestingly, this herbal powder is mentioned in Hank Williams Sr.'s song Jambalaya (On the Bayou).