For beef gravy, organize roughly 5 pounds of chuck roast, 1 large red onion, 4 tablespoons of all-purpose flour and 1/4 cup of cider vinegar. Reserve the pan juices created by the roast and thicken it over a medium-low heat to the desired consistency.
Line an extra-large roasting pan with aluminum foil, shiny side up, so that ample foil remains along the sides to cover the meat. Place the roast, now flavored with salt, pepper and the cider vinegar, inside the pan with the red onion sliced on top. Seal it in the foil. Add 1/2 inch of water to the pan, and roast the meat for approximately 3 to 4 hours or until tender. When the roast is done, remove the foil package from the pan, carefully letting any trapped liquids drain into the pan beforehand.
Transfer all the liquid to a measuring cup, skimming away the fat that collects on the surface. Save roughly 4 tablespoons. Next, measure the juices remaining. If it is less than 2 cups, supplement the difference with either water or a prepared beef stock. Add the fat and flour to the pan, and whisk vigorously over medium-low heat, forming the roux. Once the roux browns, reintroduce the remainder of the liquid, stirring everything until the texture is satiny and thickened.