Tools:
1 teacup
1 fork
1 fat separator (ideally topped with a mesh strainer to catch burnt pieces)

1. Thoroughly combine flour and just enough water in a teacup using a fork to make a liquidy paste. Set aside.
2. Scrape up burnt drippings in roasting pan. Pour drippings into fat separator with strainer. Set aside.
3. Place roasting pan across two burners. Pour drippings from fat separator back into pan, being careful not to re-add fat.  (A little fat is OK.) Turn on both burners, add broth and slightly simmer (bubbles just barely breaking the surface).
4. KEY: start vigorously whisking a small part of the hot broth with a fork, making a small whirlpool. Then once you have the whirlpool, gradually add into it a stream of the flour/water liquid. Once it starts to thicken, then go around the pan and repeat whirlpool stream method until the entire pan of gravy is thickened.  (Note: the more you whisk, the less likely you will have lumps.) Increasing the temperature to a rolling simmer helps in thickening the gravy, however, you may add more flour/water until you get the preferred consistency.
5. Adjust seasonings by adding sea salt and freshly cracked pepper. Keep warm over stove until ready to serve. 

Tip

To add more flavor to your drippings, and ultimately, to your gravy, add some carrots, whole, unpeeled garlic cloves and pearl onions to the roasting pan. Some people (myself included) forego a roasting rack and roast directly onto carrots, celery stalks, root vegetables and onions.

Giblet & Neck Broth:

Put those giblets (neck and organs, minus the liver) to use while roasting your bird. Simply fill a small saucepan 3/4 way with water, add giblets and a dash of vinegar, bring to a soft boil then simmer (bubbles barely breaking the surface) for at least two hours. Add water as necessary if water line falls below giblets.

Ways To Add Your Own Twist:

Every family has their “secret” way of adding flavor to gravy. For some, it’s sautéing minced shallot in the defatted pan drippings (before adding the broth), or adding a splash of soy sauce, white wine, cayenne, cinnamon or freshly grated nutmeg while others add herbs. One woman I saw on TV said her family didn’t like onions so she would slice an onion in half and sauté it in the gravy to intensify the flavor without the onion bits.