Place the beef stew meat, potatoes, carrots, and onion into the slow cooker.
In a small bowl, whisk together the beef broth, tomato paste, flour, Worcestershire sauce, garlic, thyme, salt, and pepper until smooth.
Pour the broth mixture over the meat and vegetables in the slow cooker. Add the bay leaf on top.
Cover and cook on low for 8 hours until the beef is tender and the vegetables are soft.
Remove and discard the bay leaf before serving.