For the beef marinade:

• 1 pound (450 g) flank steak, sliced thinly against the grain
• 1 tablespoon (15 ml) dry sherry (or Shaoxing wine)
• 2 tablespoons (30 ml) oyster sauce
• 1 tablespoon (8 g) cornstarch

For the stir-fry:

• ¼ cup (60 ml) vegetable oil (divided)
• 3–4 medium yellow onions, thinly sliced 
• 1 pound (450 g) broccoli, cut into bite-sized florets
• 1 teaspoon (4 g) sugar
• 1 teaspoon (6 g) salt
• Cooked white rice, for serving

Optional (highly recommended for extra sauce):

• 2–3 tablespoons additional oyster sauce or a splash of soy sauce
• 1–2 cloves garlic, minced (adds great depth)
• Handful of spring onions, sliced, for garnish
• Freshly ground black pepper or a pinch of chili flakes

Instructions

1. Marinate the beef: In a medium bowl, mix the sliced flank steak with the dry sherry, 2 tablespoons oyster sauce, and cornstarch. Toss well until the beef is evenly coated. Let it sit for at least 10 minutes (or up to 30 minutes in the fridge) while you prep the vegetables.
2. Stir-fry the vegetables: Heat 1 tablespoon of the vegetable oil in a large wok or heavy skillet over medium-high heat. Add the sliced onions and broccoli florets. Stir-fry for about 3 minutes until the onions start to soften and the broccoli turns bright green. Sprinkle in the sugar and salt, toss to combine, then remove the vegetables to a plate and set aside.
3. Cook the beef: Add the remaining 3 tablespoons of oil to the same wok. When the oil is hot and shimmering, add the marinated beef in a single layer (work in batches if needed to avoid crowding). Stir-fry for 2–3 minutes until the beef is mostly browned but still slightly pink inside (it will continue cooking later).
4. Combine everything: Return the cooked onions and broccoli to the wok with the beef. Add any optional extra oyster sauce, minced garlic, or black pepper. Stir-fry everything together for another 1–2 minutes until the beef is just cooked through and the sauce nicely coats the ingredients.
5. Serve immediately over hot steamed white rice. The dish is best enjoyed right away while everything is still hot and crisp-tender.

Tips for Success

• Slice the beef properly: Freezing the flank steak for 20–30 minutes makes it much easier to slice thinly against the grain — this is the secret to tender results.
• High heat is key: A hot wok gives you that restaurant-style sear and prevents the beef from stewing in its juices.
• Don’t overcook the broccoli: It should stay bright green and have a slight crunch.
• Make it saucier: If you like more glossy sauce (like classic takeout), stir in ¼ cup water or beef broth mixed with an extra teaspoon of cornstarch at the end and let it bubble until thickened.
• Variations: Add minced garlic and ginger with the vegetables for more authentic flavor, or toss in sliced bell peppers or carrots for extra color and crunch.

This simple stir-fry is naturally gluten-free if you use gluten-free oyster sauce. It’s a family favorite that beats delivery any night of the week!