Prepare Beef
Slice flank steak ¼-inch thick. Rinse slices in water.
Mix baking soda, cornstarch, oyster sauce, soy sauce, tamari, white pepper, water, cooking wine, and sugar.
Drain beef, squeeze dry. Add beef to marinade and mix.
Add 1 tbsp cooking oil to marinated beef.
Prepare Aromatics and Noodles
Separate rice noodles.
Slice onion. Separate scallion whites from greens.
Cook Beef and Aromatics
Heat 3 tbsp cooking oil.
Fry onion and scallion whites for 20-30 seconds until fragrant.
Add beef and cook 1 minute. Turn off heat, add sesame oil.
Finish Dish
Mix tamari, soy sauce, and oyster sauce.
Add noodles, bean sprouts, scallion greens, and sauce mixture to the pan. Stir-fry until noodles are heated through and coated.
