Marinate the Beef:

Mix the beef slices with soy sauce, cornstarch, and sesame oil. Let it marinate for at least 15 minutes.

Prepare the Noodles:

If the rice noodles are refrigerated or stiff, soften them according to package instructions, usually by warming them in the microwave or blanching them quickly in boiling water. Be careful not to overcook.

Stir-Fry the Beef:

Heat half of the vegetable oil in a wok or large skillet over high heat. Add the beef and stir-fry until just cooked through. Remove the beef and set aside.

Cook the Vegetables:

Add the remaining oil to the wok. Sauté the garlic and onions until fragran

Combine Ingredients:

Add the noodles to the wok along with soy sauce, oyster sauce, dark soy sauce, and sugar. Stir-fry, ensuring the noodles are coated with the sauce and have taken on some color.

Finalize the Dish:

Return the beef to the wok, add the bean sprouts and green onions, and stir-fry for another 1-2 minutes. Adjust the seasoning with salt and pepper.

Serve:

Serve hot, allowing the flavors of the sauce to permeate the noodles and beef.