Thickening Your Sauce
Using high heat to reduce the excess liquid in a sauce is the simplest method used in thickening a sauce. This method intensifies the flavor and is also used to vaporize the alcohol from wines and liquors. When the sauce has congealed enough that it will coat the back of a spoon without running off, it is complete. You will want to hold off on seasoning your sauce after it is complete or near completion, because the reducing will naturally cause the sauce to become saltier.