Trim any fat from the beef and toss with salt and pepper.
Heat 1 tablespoon of oil over medium-high heat in large pot or Dutch oven. Add the seasoned beef and cook in small batches until browned. Transfer the beef to a bowl and set aside.
Reduce the heat to medium and add the remaining oil. Add the onion and cook until softened, about 5 to 7 minutes.
Add the beef, beef broth, condensed onion soup, Worcestershire sauce, and bay leaf to the pot. Bring to a boil, cover, and reduce heat to a simmer. Simmer for 1½ to 2 hours or until beef is fork-tender.
To thicken the gravy, combine cornstarch with ⅓ cup cold water. Pour into the beef mixture a little at a time while stirring until it reaches the desired consistency.
Taste and season with additional salt and pepper if desired. Discard bay leaf and serve over mashed potatoes.
