There are three basic ways to thicken a gumbo, the traditional Louisiana stew: okra, filé powder made from the leaves of sassafras trees, and roux. One, two, or even all three of these may be used in a single gumbo, depending on the cook’s preference and the season.
diobahn, for instance, uses both a medium-color roux and okra to thicken gumbo, then passes home-ground filé powder at the table for people to use as they please. Filé powder should not be cooked in with the gumbo, says MakingSense, because it takes on an unpleasantly slimy, stringy texture.
JungMann doesn’t think okra and filé powder belong in the same pot—okra is a hot-weather vegetable, and filé powder is meant to be used only when okra is unavailable. Major504 makes gumbo with neither okra nor filé powder but thickens with only a dark “mahogany roux” made with oil, not butter.
MakingSense cooks gumbo with okra in the summer months when it’s available and filé powder in the winter months—especially in duck season, because the filé powder goes well with duck.
None of these methods is necessarily more authentic than the others. “The right way to make it is usually how your own mama made it,” says WCchopper.
Board Link: Remedial gumbo question