Filé powder is actually ground sassafras. It is often seen on grocery store shelves as Filé Gumbo, as it is filé powder that is traditionally used in gumbo to both thicken the stew as well as add a unique flavor. Gumbo is a traditional Louisiana stew, generally comprised of seafood, chicken & sausage. Another method used to thicken the gumbo stew is the use of okra. Filé is used not just in gumbo, but in many other Cajun and Creole dishes. The flavor is often described as being a little like root beer, while others describe it as having undertones of eucalyptus.
It is recommended that the filé powder be added to stews, soups and sauces near the end of cooking, as overcooking it, or bringing it to a boil, will result in a stringy texture. While many cooks stir the filé powder into their pots just before serving, others put out small dishes of filé powder so that each person can add the amount they want right at the table.
Filé makes a great gluten-free thickener.