If there's time, place steak in freezer for 10-20 minutes to make slicing easier. Holding knife at 45-degree angle, thinly slice steak. Toss steak with 1 t. soy sauce in small bowl and let stand 10-20 minutes (while preparing vegetables).
Heat large wok or skillet over high heat 30 seconds. Add oil and swirl to coat surface. Heat just until oil starts to smoke. Add scallion, ginger, and garlic and heat until fragrant, about 20 seconds. Add beef and stir-fry until lightly browned, about 1 minute. Add pepper and peas and stir-fry just until pepper wilts, about 20 seconds. Stir in corn, remaining 2 t. soy sauce, and the oyster sauce. Cook and stir just until meat is cooked through, about 1 minute. Serve at once with rice.