Mix water, soy sauce, Seasoning, cornstarch and ginger in small bowl until smooth. Set aside.
Heat oil in large nonstick skillet on medium-high heat. Add beef in batches; stir fry 5 minutes or until no longer pink. Add additional oil if needed. Remove beef from skillet. Add vegetables to skillet; stir fry 3 minutes. Return beef to skillet.
Stir soy sauce mixture. Add to skillet; stirring constantly, bring to boil on medium heat and boil 1 minute. Serve with cooked rice, if desired.