01 - Combine the sliced beef with 2 tbsp soy sauce, 1 tbsp cornstarch, and 1 tsp sesame oil in a bowl. Mix thoroughly to coat and let marinate for at least 10 minutes to tenderize.
02 - Whisk together 3 tbsp soy sauce, 2 tbsp oyster sauce, 1 tbsp rice vinegar, 1 tbsp brown sugar, 2 tbsp water, and 1 tsp cornstarch in a small bowl until smooth and fully combined. Set aside.
03 - Heat 1 tbsp vegetable oil in a large wok or skillet over high heat until smoking. Add marinated beef in a single layer and sear for 1-2 minutes until browned but slightly undercooked. Transfer to a plate, reserving juices.
04 - Add remaining 1 tbsp oil to the wok. Stir fry garlic, ginger, and white spring onion parts for 30 seconds until fragrant, being careful not to burn.
05 - Add carrots and stir fry for 1 minute. Add snow peas and continue stir frying for 2 minutes until vegetables are tender-crisp.
06 - Return beef and accumulated juices to the wok. Pour in prepared sauce and toss everything together. Stir fry for 2-3 minutes until sauce thickens and coats all ingredients, and beef reaches desired doneness.
07 - Remove from heat immediately. Garnish with reserved green spring onion slices. Serve hot over steamed jasmine rice or noodles.