To make a simple pan gravy, deglaze the roasting pan with liquid after removing the roast, then simmer the drippings with flour or cornstarch slurry until thickened and seasoned to taste.
A simple pan gravy made from roast drippings adds incredible flavor and depth to any meal. After you've removed your roast and allowed it to rest, pour off most of the excess fat from the roasting pan, leaving behind the flavorful brown bits (fond) and about 2-3 tablespoons of fat. Place the roasting pan over medium heat on the stovetop (if it's stovetop-safe, otherwise transfer the drippings to a saucepan). Add about 1/4 cup of flour (for every 2 tablespoons of fat) to the pan and whisk continuously for 1-2 minutes to create a roux, cooking out the raw flour taste. Slowly pour in about 2-3 cups of liquid, such as beef or chicken broth, wine, or water, whisking constantly to prevent lumps and scrape up all the browned bits from the bottom of the pan. Bring the mixture to a simmer, whisking frequently, and let it cook for 5-10 minutes, or until the gravy thickens to your desired consistency. If it's too thin, you can continue to simmer; if too thick, add more liquid. Season the gravy generously with salt and black pepper to taste. For an extra rich flavor, you can stir in a pat of butter at the end.
For a smoother gravy, strain it through a fine-mesh sieve after cooking to remove any lumps or small bits of fond before serving.