Trim fat from beef. For easy slicing, wrap and freeze beef 30 to 45 minutes or until firm. Thinly slice beef across grain; place slices in self-sealing plastic bag. In a second self-sealing bag combine sweet pepper, zucchini, and onion.
For marinade, in bowl combine ginger beer, soy sauce, and garlic. Divide marinade between beef and vegetables. Seal bags; turn to coat each. Refrigerate 4 to 6 hours, turning bags occasionally. Drain marinades into bowl. Stir in cornstarch; set aside.
Heat oil in large nonstick wok or extra-large nonstick skillet over medium-high heat. Add ginger; stir-fry 15 seconds. Add vegetables; stir-fry 3 to 5 minutes or until crisp-tender. Remove vegetables. Add half the beef to wok. Stir-fry 2 to 3 minutes or until beef is slightly pink in center. Remove beef. Repeat with remaining beef. Return all to wok, away from center. Stir marinade mixture; add to center of wok. Cook until bubbly. Toss beef and vegetables to coat. Remove from heat.
To serve, divide beef and vegetables among lettuce leaves, top with cilantro, and roll up. Makes 12 wraps (4 servings).