Cornstarch has almost twice the thickening power of flour, so use about half of much. Also, another nice perk about cornstarch is that it's almost impossible to end up with lumps, a common occurrence in gravies using flour, and, it's gluten free!
Mix about one tablespoon of cornstarch with 1/2 cup of ice water. Whisk it thoroughly in a bowl for a few seconds until it's an even white liquid. You're probably asking yourself, "this doesn't look very thick, what's up Noah?" Patience, patience, the cornstarch has to be heated to above 200 degrees F before it thickens.
- You may need to make more or less of this mixture depending on how much gravy you're making.