Remove cooked meat from roasting pan. Place roasting pan on large cooking element, and turn it to medium-high heat setting. Heat the drippings, allowing them to come to a boil. Sear the bottom of the pan while swirling the juice with the bottom of a large cooking spoon. If potato water is available, add this to the pan. If a large amount of gravy is needed, add water as well. 

Add 1 tablespoon of:  liquid BEEF bouillon for BEEF gravy, or liquid CHICKEN bouillon for CHICKEN/TURKEY gravy. Stir into drippings.

Make a watery paste of water and cornstarch, OR water and flour. If using flour, whisk or blend with a handheld blender until all lumps are removed. While swirling the juice with the bottom of the large cooking spoon, start adding a small amount of the paste. Allow the drippings to come to a rolling boil. If the drippings are too watery, add more paste, and once again allow the drippings to boil. Continue this until the drippings reach the desired consistency.  

GRAVY CONSISTENCY - Your gravy should be slightly runny.

Test flavour of the gravy and if necessary, add a second tablespoon of bouillon. 

Pour gravy into gravy boat and serve.

NOTE - CORNSTARCH is easy to mix. The gravy surface will be shiny in appearance.  FLOUR is more difficult to mix. The gravy surface will be dull, but the gravy reheats better than cornstarch gravy.