Flank steak is flash-fried with abundant fresh scallions and a splash of soy sauce in this minimalist Cantonese classic. High protein and quick to prepare, it embodies the clean eats philosophy of Chinese wok cooking.
Slice the flank steak thinly across the grain; toss with cornstarch, 1 tbsp soy sauce, Shaoxing wine, and set aside for 10 minutes to marinate.
Trim scallions and cut into 2-inch segments, separating whites and green parts for optimal texture.
Heat a wok or large skillet over high heat until just beginning to smoke, then add neutral oil and swirl to coat.
Quickly sear the beef in a single layer, undisturbed, for about 45 seconds, then stir-fry until barely cooked through; transfer beef out.
Add scallion whites and sauté for 30 seconds; return beef and add scallion greens, the remaining soy sauce, sugar, and black pepper.
Stir-fry everything together over high heat for 1 minute until scallions are vibrant; serve immediately without overcooking.