I just read the lyrics to "Jambalaya" in DigiTrad, and I would like to point out one small error. It should be "file gumbo", not "filet gumbo". There should be an accent mark over the "e" - what is called an "accent ague" in French. (I don't know how to represent these things in HTML.) "Filet" does do a good job of representing the pronunciation, while "file" without the accent mark, could be totally misleading to someone who doesn't know what file powder is.

Then again, I am only familiar (somewhat) with European French, not Cajun French. For all I know, maybe Cajuns have dropped accent marks.

Anyway, file powder, I understand, is a flavoring made from ground sassafras leaves, and it has that root-beer flavor that is familiar to Americans. See http://www.foodsubs.com/Herbs.html#gumbo

Let's see if this works: "filé powder".