Mix 2 tablespoons of cornstarch with ¼ cup of water. Stir in 1 teaspoon of sugar, 1 tablespoon of dark soy sauce, 1½ tablespoons of light soy sauce, 1 tablespoon of Shaoxing wine, and ⅛ teaspoon of five-spice powder.
Slice 360g of flank steak ¼in / 5mm thick against the grain. Toss with about a fifth of the sauce and set aside.
Boil 4 cups of broccoli florets for 1 minute, then drain.
Heat 2 tablespoons of vegetable oil in a wok over high heat. Sear the beef for 1 minute, then add 1 finely chopped garlic clove and 1 teaspoon of finely chopped ginger.
Add the remaining sauce and 1 cup of water. When it bubbles, add the broccoli and simmer for about 1 minute, until the sauce thickens.
