filé powder
Filé (pronounced “FEE-lay”) powder is the ground, dried leaves of the sassafras tree. A traditional ingredient in the cuisines of Louisiana, it smells like eucalyptus and adds an earthy flavor. It’s not merely a spice; filé also thickens gumbos and other soups. Filé can turn stringy when added to boiling liquid, so be sure to add it only when you’re about to serve your gumbo (and if you’re making the gumbo ahead, don’t add the filé until after you’ve reheated it).