In a large skillet, brown beef in oil; drain. Transfer to a 3-qt. slow cooker. , Add the broth, beer, onion, barley, garlic, oregano, parsley, Worcestershire sauce, pepper flakes, pepper, salt and bay leaf. Cover and cook on low, 8-10 hours. , Stir in vegetables; cover and cook until meat is tender and vegetables are heated through, 30 minutes longer. Discard bay leaf.