Stir broth into cornstarch in a small bowl.Add soy sauce, sugar and salt. Stir & set aside.
Heat wok or large frying pan on Medium-high heat until very hot. Add cooking oil. Add brocoli,carrots, celery and onion. Stir fry until tender crips approx 10 minute Add cashews and toss a minute longer. Stir in broth mixture for approximately 2-3 minutes stirring constantly until thickened. Serve topped with roasted sesame seeds and additional cashews if desired.