What is a suitable flour substitute for gravy?

A suitable flour substitute for gravy is cornstarch. Cornstarch is a gluten-free option that can be used to thicken gravy in a similar way to flour. To use cornstarch as a substitute, you typically need to mix it with cold water to create a slurry before adding it to the gravy. It is important to note that cornstarch has a higher thickening power than flour, so you will need to use less of it to achieve the desired consistency.