01 - Combine beef slices with 1 tbsp soy sauce, 1 tsp cornstarch, and 1 tsp sesame oil in a medium bowl. Let marinate for 10 minutes.
02 - Whisk together soy sauce, oyster sauce, hoisin sauce, rice vinegar, brown sugar, cornstarch, and water in a small bowl. Set aside.
03 - Heat 1 tbsp vegetable oil in a large wok or skillet over high heat. Add marinated beef in a single layer and sear for 1-2 minutes until browned. Remove and set aside.
04 - Add remaining 1 tbsp oil to the wok. Stir-fry garlic, ginger, and spring onions for 30 seconds until fragrant.
05 - Add bell peppers, carrot, sugar snap peas, and broccoli florets. Stir-fry for 3-4 minutes until vegetables are tender-crisp.
06 - Return beef to the wok. Stir the sauce mixture, then pour over the beef and vegetables. Stir-fry for 2-3 minutes until sauce thickens and everything is well coated.
07 - Serve hot with steamed rice or noodles as desired.