Gravy is a sauce and is usually just broth thickened with cooked flour. The broth-flour mixture doesn’t become thickened until the flour cooks, usually at boiling temperature. Most gravy tastes better if some of the fat is left in the broth. However too much fat in the broth can be bad for your health. Gravy is best smooth. So if onions, celery, or other vegetables are added, make sure they are finely chopped and cooked until soft. I prefer finely chopped green onion, a wee bit of finely grated celery and a wee bit of finely grated carrot.
Remember that flour tastes better than corn starch. Mashed potato can be used to thicken gravy also. Flour will not stir into very hot broth. Cool broth to below 120 degrees before adding flour. Always add flour with a whisk. You can also use a roux (cooked butter & flour). Flour can be added by stirring lots of flour (6 Tablespoons flour into 1 cup broth) into cold broth and dribbling the cold broth & flour mixture into cooking gravy while stirring briskly with a whisk.
Poultry Spices good for gravy:
Use 80% Chicken Broth.
Use roasting pan drippings if available.
Remove excess fat.
Deglaze pan with a bit of hot water.
Put in big pot; add spices and green onion to taste.
Bring to boil and simmer for 10 min to soften green onion.
Taste and adjust spices or salt as necessary.
Cool broth by placing into cold water.
Add three tablespoons of flour per pint of gravy.
Stir briskly continuously with a whisk while cooking on high heat until boiling.