At this point determine the thickness & consistency of the the sauce. To thicken the sauce, whisk 1 T cornstarch into the remaining vegetable broth. Add a small amount of the cornstarch mixture to the sauce, stirring constantly. Stir until the sauce thickens. If needed, add more cornstarch, whisking until smooth. Repeat until the sauce is the desired thickness. Note: make sure you have additional vegetable broth in case you need additional thickening (1 T cornstarch to 1/4 cup broth).