Heat oil in large nonstick skillet on medium-high heat. Add bell peppers and onion; cook and stir 4 minutes or until tender-crisp. Add beef; cook and stir 5 minutes or until desired doneness.
Mix water, soy sauce and Seasoning Mix until well blended. Add to skillet; stirring constantly, bring to boil on medium heat and boil 1 minute or just until sauce is thickened.
Serve with cooked rice, if desired