In a Dutch oven or large kettle, cook beef and onion over medium heat until meat is no longer pink; drain. Add the broth, vegetables, tomato paste, Worcestershire sauce, thyme, salt and pepper. Bring to a boil. Reduce heat; cover and simmer for 30-40 minutes or until vegetables are tender.
In a small bowl, combine the cornstarch and water until smooth; stir into the stew. Bring to a boil; cook and stir for 2 minutes or until thickened.