Pot roast is a wonderfully forgiving dish that's hard to mess up. Long, slow braising tenderizes the tough chuck roast so it becomes flavorful and juicy. Aromatic vegetables, such as onions, celery and carrots also add flavor. Top it off with a gravy made from corn starch and you've got a hearty, satisfying meal that took almost no effort.
The reason you add cornstarch to a pot roast is to create a thick, flavorful gravy. Cornstarch, which comes from the endosperm of the corn, has been dried, processed and ground to create a fine, gluten-free powder. When heated in a liquid, it has excellent thickening power. You can also use flour, but it's usually first combined with butter to form a beurre manie, or "kneaded butter," which is a paste made of equal parts butter and flour -- an extra step that adds flavor, but also fat and calories. Cornstarch is simpler because you can mix it with a little cold water and add it directly to the pot roast.
Oven-Braised Pot Roast
To make a gravy for oven-braised pot roast, try removing the pan from the oven when the pot roast and vegetables are completely tender. Transferring the meat and vegetables to a serving dish and covering them with foil will keep them warm. Make a slurry by whisking cornstarch and a little cold water together. Whisk this slurry into the drippings in the remaining liquid in the pan. Simmer, stirring constantly, until the gravy thickens. Pour the gravy over the meat and vegetables or pour it into a gravy boat.
Slow-Cooker Pot Roast
To make a gravy for a slow cooker pot roast, transfer the meat and vegetables to a serving dish once they're completely tender. Covering them with foil will keep them warm. Another option is to simply move the meat and vegetables to one side of the slow cooker. Combining cornstarch and cold water in a bowl and pouring this mixture into the hot liquid in the slow cooker makes the beginnings of a tasty gravy. Cover the cooker and turn the temperature to high. Cook for 10 to 15 minutes, or until thickened, stirring occasionally.
Potential Pitfalls and Solutions
Cornstarch is inexpensive, simple to use and widely available. It has little flavor and creates a glossy, translucent gravy. One problem with cornstarch, though, is that it thickens almost immediately when introduced to a hot liquid. You must mix it with a cold liquid first or you'll get lumps. It also breaks down under high heat. Some slow cooker recipes call for adding the cornstarch at the beginning of the cooking time. If you choose to go this route, be sure to keep the slow cooker on low so the cornstarch doesn't break down.