In a mixing bowl, combine thinly sliced flank steak with water, Shaoxing rice wine, salt, baking soda, cornstarch, and a bit of oil. Mix for about 2 minutes and marinate for 10-15 minutes.

If using rice vermicelli, heat oil in a wok to 350°F. Fry the rice noodles for about 30 seconds until golden, then drain on paper towels.

In the same wok, heat oil over medium-high heat. Add the marinated beef and sear it for 2-3 minutes until golden brown. Remove and set aside.

Add minced garlic and white parts of green onions to the wok. Stir-fry for 30 seconds until fragrant.

Return the beef to the wok, add black pepper and a splash of Shaoxing rice wine. Stir-fry for another minute.

Sprinkle in sugar and pour in soy sauce, stirring until the beef is well-coated and the sauce thickens, about 1-2 minutes.

Stir in the green onion tops and serve immediately over rice vermicelli or steamed rice.