Choctaw Indians from the Louisiana bayou country are said to have been the first users of this seasoning made from the ground, dried leaves of the sassafras tree. It's since become an integral part of creole cooking and is used to thicken and flavor gumbos and other Creole dishes. Filé has a woodsy flavor reminiscent of root beer. It must be stirred into a dish after it's removed from the heat because undue cooking makes filé tough and stringy. Filé powder is available in the spice or gourmet section of most large supermarkets. As with all spices, it should be stored in a cool, dark place for no more than 6 months.