In a medium bowl add your sliced beef, shaoxing wine, 1 tablespoon of tamari sauce, white pepper and cornstarch and allow to marinade with your rice noodles are soaking.
Soak your dried rice pad thai (medium thick) noodles in a bath of hot water for about 3-5 minutes or just until they start to softened but not completely al dente as they will continue to cook in while they are fried. Rinse noodles with cool water, drain and set aside.
Put oil in your wok (frying pan) and turn on medium-high heat . Once the temperature is at medium heat add the onions and garlic and fry for a minute just until the aroma hits your nose.
Add your marinated beef to the pan and stirfry for a minute or two or just until turns golden brown. Remove beef and onions to plate and keep warm and set aside. (If you wanted to cook some other veggies then you would add them at this point)
Add your presoaked noodles to the seasoned pan turn up the heat to medium high and about 1 tablespoon of water and move the noodles quickly around in the pan keeping them separated so they do not stick. (feel free to add a little more oil or a little more water just to prevent sticking and to confirm that your noodles are aldente- test a noodle)
Add your beef mixture back to the noodles and add XO sauce, Tamari (soy sauce), oyster sauce, mung beans and mix until well incorporated.
Serve Pan Fried Beef Noodles with Spicy XO Sauce with a sprinkle of green onions for garnish and get ready to make second helpings...