Start by preparing any sauce you'd like according to the recipe. Here, we are making a sweet orange sauce for desserts. To thicken the sauce, whisk starch in water to dissolve. Mixing before you add to the sauce will keep the sauce from getting lumpy.
Whisk some of the starch-water mixture into the sauce. Add a bit at a time until the sauce reaches desired consistency. Don't add it all at once, or the sauce might become too thick. Remove from heat to stop the thickening process. Serve and enjoy!