1. Slice the flank steak thinly against the grain and place in a bowl.

2. In the bowl with beef, add 1 tablespoon soy sauce, 1 tablespoon cornstarch, and sesame oil; toss and marinate for 10-15 minutes.

3. Blanch broccoli florets in boiling water for 1-2 minutes until bright green, then drain and rinse under cold water.

4. Whisk together remaining soy sauce, oyster sauce, beef broth, sugar, and a pinch of cornstarch in a small bowl; set aside.

5. Heat 1 tablespoon vegetable oil in a wok or large skillet over high heat until hot.

6. Add marinated beef in a single layer, searing for 1 minute per side until just cooked; remove and set aside.

7. Add remaining oil, then stir-fry garlic and ginger for 30 seconds until fragrant.

8. Toss in broccoli and stir-fry 1 minute, then return beef to the pan.

9. Pour sauce mixture over beef and broccoli, stirring constantly until sauce thickens and coats evenly, about 1-2 minutes.

10. Serve immediately with steamed rice.