Heat oil in large nonstick skillet or wok over medium-high heat until hot.
Add beef and onion; cook and stir 2 to 3 minutes or until beef is browned. Remove from skillet; cover to keep warm.
In same skillet, combine potatoes, green beans, broth, thyme, pepper and Worcestershire sauce. Bring to a boil. Reduce heat; cover and simmer 15 to 20 minutes or until vegetables are tender.
In small bowl, combine water and cornstarch; blend well. Add beef mixture, cornstarch mixture and parsley to vegetables; cook and stir until thickened and bubbly.