Filé powder is used as a spice and a thickener in soup, stews and gumbos. It is made from the dried ground leaves of the Sassafras tree. It has been used by Native Americans and later in Cajun cooking.
When I was growing up in the 1960s we would dig Sassafras roots in the early spring and make tea out of them. My Grandma said they were a tonic. Fast forward to the 1980s and I became aware that the FDA has determined that sassafas contained a carcinogen called safrole. I believe the research was done in the 1960s and 70s but alas there was no Internet then so it took awhile for the word to get around. Anyway it was no longer sold for or considered safe for human consumption. Later testing has determined that the safrole is primarily in the roots and the bark,there is not enough in the leaves to show up in normal testing so filé powder has been declared safe. It just so happens I have many Sassafras trees on my land so I decided to give it a try.
Harvesting is easy, just nip off small branches. Snip off any leaves that have insect damage and dry the good leaves in a dark, dry spot. Once the leaves have dried to a crumbly consistency just use your food processor or grinder. You want a powder. Then store in a dark jar out of direct sun.
Using your filé powder is pretty easy too. You can just set it on the table and let folks sprinkle it on their food once it is served. If you put it in while the food is cooking or being reheated it will get ropy or stringy, very unpleasant. Most of the recipes I found using it are robust, spicy meals so the cool (to me) flavor of the filé powder would be a nice balance and to thicken it to your own preference sounds like a winner as well. So put on some gumbo and some fiddle music and enjoy the bounty of the land!