01 - Combine beef slices with soy sauce, cornstarch, and sesame oil in a bowl. Toss thoroughly to coat and let stand for 10–15 minutes.
02 - Whisk together soy sauce, oyster sauce, hoisin sauce, rice vinegar, sriracha, brown sugar, and water until smooth. Set aside.
03 - Heat 1 tbsp oil in a large wok or skillet over high heat. Add beef in a single layer and sear for 1–2 minutes per side until browned. Transfer to a plate.
04 - Add remaining 1 tbsp oil to the wok. Stir fry garlic and ginger for 30 seconds until fragrant.
05 - Add broccoli and bell pepper. Stir fry for 2–3 minutes. Pour in 2 tbsp water, cover, and steam for 2 minutes until broccoli reaches tender-crisp.
06 - Return beef to the wok. Pour in prepared sauce and toss everything together. Stir fry for 2–3 minutes until sauce thickens and coats evenly.
07 - Remove from heat. Garnish with green onions and sesame seeds. Serve immediately with steamed rice or noodles.