Prepare the Stir-Fry Sauce by mixing light soy sauce, dark soy sauce, oyster sauce, sugar, salt, and white pepper in a bowl and whisk until dissolved.

Marinate the beef by combining it with 1 tablespoon of the sauce, 1 tablespoon of cornstarch, and just enough water to lightly coat it.

Heat the wok over high heat until smoking, add vegetable oil, swirling to coat the pan.

Sauté aromatics – garlic, ginger, and white parts of scallions in hot oil for about 30 seconds until fragrant.

Cook the beef for 3-5 seconds until it turns pale and slightly brown; do not overcrowd.

Cook the shrimp in the same wok for around 30 seconds until pink and opaque.

Combine the beef and shrimp in the wok, add green parts of scallions and sliced chili peppers, pour in remaining sauce and stir quickly.