We recommend: King Arthur Gluten Free Tapioca Starch ($8)
Flavor Notes: This neutral-tasting, jellying starch thickens quickly at low temperatures, so it's the perfect starch to use if you need to correct the thickness of your gravy right before serving.
How to use: You'll need one tablespoon per cup of liquid. Whisk tapioca starch in a tablespoon of cold water. Then whisk slurry into hot liquid. Stir until thickened, and serve.