Add beef to a medium bowl and pour 1 tablespoon of water on it. Mix with chopsticks until the water is absorbed. Now add the marinade ingredients and let the beef marinate for 20-30 minutes at room temperature.
Heat oil in a deep non-stick pan or wok. Fry the beef, separating the pieces, until they’re no longer pink. Remove from the oil and place on a wire rack.
Leave a bit of oil in the pan and stir-fry the noodles until they start to curl up.
Add garlic, half of the bean sprouts, and onion, and stir-fry until they become soft. Pour soy sauce and oyster sauce into the pan and mix to coat the noodles.
Add the cooked beef back to the pan along with the other half of the bean sprouts, the chives, and the green onions. Stir-fry for 1-2 minutes to coat in sauce and heat the beef. Serve hot and enjoy!