Sassafras is a North American tree. Both its leaves and bark have been used in cooking for centuries, first by Native Americans and then later by European colonists. They continue to have numerous culinary applications and show up in several traditional recipes. The flavor of sassafras is considered unique among seasonings, which means that it should be considered first if your recipe calls for it; however, it is not always the easiest seasoning to find. If you cannot get your hands on this herb, consider one of the sassafras substitutes.
Your best bet: Okra
One of the best-known uses of sassafras is in the form of file powder. File powder is made with ground sassafras leaves and is used as a thickener for certain dishes that have their origin in Louisiana. Those dishes include gumbo and jambalaya, both of which have traditionally been made using either file powder or okra. In fact, the question of which is the better thickener is still the subject of heated debates among Louisiana’s cooks. For the record, the earliest incarnations of gumbo were made with okra.
Both okra and file powder are mucilaginous in that they contain mucilage, a soluble fiber with multiple health benefits and this is what gives them their thickening properties. The texture of the dish will be essentially the same no matter which you use. The main difference will be that you get extra bulk because of the okra pods. This may or may not be a bad thing, depending on how you feel about okra.
If you decide to use okra, note that it differs from file powder in that you will have to add it early in the cooking process.
A decent second choice: Roux
The heated mixture of fat and flour is a classic way to thicken dishes. Like both file powder and okra, a roux can serve as a way to thicken stews and other similar dishes while also providing a distinctive flavor. When making a roux for gumbo, the cook will often try to get the mixture as dark as possible. Many gumbo recipes will also use a roux along with okra or file powder. If thickening with mucilage does not appeal to you, a roux by itself will work just fine.
In a pinch: Root beer
If you want the flavor of sassafras in your dish and do not need a thickener, root beer is your best option. Many commercial root beer blends contain sassafras, but with its safrole removed. Safrole is a compound in sassafras that the FDA has determined is toxic. Root beers that do not contain actual sassafras will typically contain other flavorings that mimic its flavor.
Note that since root beer is typically very sweet, it will be necessary to limit its use to dishes where sweetness will not negatively affect the overall flavor profile.
The flavor of anise can work as a substitute for that of sassafras and it is used as a sassafras substitute in some gumbo recipes. Note that anise can be a potent spice and must be used in moderation. Note also that it is not a thickener.
Arrowroot is thickener that has been around for some time and which has recently had a resurgence because it does not contain gluten. Arrowroot’s appearance is similar to that of cornstarch and it is used in the same way by—making a slurry with water and adding it to the food that you want to thicken.