Add the beef stew meat to the slow cooker.
Layer the sliced onions on top of the beef.
In a bowl, stir together the beef broth, French onion soup mix, Worcestershire sauce, thyme, and black pepper.
Pour the broth mixture over the onions and beef.
Cover and cook on low for 8 hours until the beef is fork-tender.
Ladle the stew into bowls and serve with crusty bread on the side.