Prepare the sauce: In a small bowl, combine water, soy sauce, honey, cornstarch, ginger, garlic powder and pepper.
Heat a wok or large skillet over medium-high heat. Add oil and swirl to coat wok. Stir-fry beef for 3 to 4 minutes or until browned on all sides. Remove to a plate.
Add frozen vegetables and water to wok. Cover and cook, stirring frequently, for about 8 minutes or until hot and tender-crisp. Add beef, sauce and baby corn (if using). Cook, stirring constantly, until sauce is thickened and bubbling and beef is fork-tender, about 3 minutes.