Yes! I like cornstarch because it is flavorless and gluten-free, but if you prefer to use flour, you need to use 4 tablespoons of flour dissolved in 5 tablespoons of cold water. Mix it fully, then add the slurry to the broth mixture. If you use flour as the thickener, add an additional 5-10 minutes to the cooking time after it is added to the saucepan to allow the flavors to blend, otherwise you will be able to taste the flour in the gravy.