In a large bowl, combine the soy sauce, oyster sauce, fish sauce, honey, black pepper, and garlic powder. Add the thinly sliced flank steak and toss to coat well. Set aside to marinate for at least 30 minutes or up to 2 hours.
Heat a large wok or skillet over high heat. Add the vegetable oil and swirl to coat the bottom of the pan.
When the oil is hot, add the marinated flank steak and stir-fry for 2-3 minutes or until browned on the outside but still pink on the inside. Transfer the steak to a plate and set aside.
In the same wok or skillet, add the onion, red bell pepper, green bell pepper, and minced garlic. Stir-fry for 2-3 minutes or until the vegetables are tender but still crisp.
Return the cooked flank steak to the wok or skillet and toss with the vegetables. Stir-fry for an additional 1-2 minutes or until heated through.
Garnish with sliced green onions and serve hot.
Notes
Tips and Tricks
Thinly slice the beef against the grain to ensure tender and juicy pieces of meat.Marinate the beef for at least 30 minutes to allow the flavors to infuse.Use a wok or large skillet to quickly stir-fry the beef and vegetables.Cut the vegetables into thin, uniform slices to ensure even cooking.Use a wooden spoon or spatula to stir the ingredients, keeping the meat and vegetables moving to prevent sticking.