1. Slice and marinate the beef: Thinly slice the beef across the grain into 1/8–1/4‑inch strips. In a bowl, combine soy sauce, Shaoxing wine, cornstarch, and oil. Add beef, toss to coat, and let sit 10 minutes while you prep veggies.
2. Make the sauce: Whisk together soy sauce, oyster sauce, rice vinegar, brown sugar, and broth in a small bowl. Set aside the cornstarch slurry separately if you want a thicker sauce.
3. Bring a large pot of salted water to a boil. Add noodles and cook, stirring occasionally, until al dente, about 3 minutes. (If you changed noodle type or used rice please follow directions for what you used).  Drain in a colander and run under cold water until chilled. Drain well and set aside. 
4. Blanch or steam broccoli (optional for tender‑crisp): Bring a pot of water to boil, add broccoli for 1 minute, then drain and plunge into ice water to keep bright green. Drain and set aside. (Skip this step and simply stir‑fry longer if you prefer.)
5. Heat the wok/skillet: Heat a wok or large heavy skillet over high heat until very hot. Add 1 tablespoon oil and swirl.
6. Quick‑sear the beef: Add marinated beef in a single layer (work in batches to avoid crowding). Stir‑fry 1–2 minutes until just browned but not fully cooked through. Remove beef to a plate and set aside.
7. Stir‑fry aromatics and broccoli: Add remaining 1–2 tablespoons oil to the hot pan. Add the white parts of the scallions, ginger, and garlic; stir 20–30 seconds until fragrant. Add broccoli and stir‑fry 2–3 minutes until bright and tender‑crisp.
8. Combine and saucify: Return beef (and any juices) to the pan. Pour the prepared sauce over everything and toss to combine. Bring to a simmer—if using the cornstarch slurry, add it now and cook 30–60 seconds until the sauce thickens and becomes glossy.
9. Finish: Drizzle with toasted sesame oil, scatter sliced green scallion tops, and give a final toss. Taste and adjust with a pinch of salt or a splash of soy/vinegar if needed.
10. Serve: Spoon over steamed rice or toss with noodles. Sprinkle sesame seeds if desired.

Tips

• Freeze the steak for 15–20 minutes before slicing to make very thin slices easier.
• Work in batches for best sear and to avoid steaming the meat.
• For extra depth, add a splash of fish sauce or 1 tsp chili garlic sauce to the sauce.
• Leftovers keep 2–3 days refrigerated; reheat gently in a skillet with a splash of water or broth.