Start by marinating the flank steak. In a bowl, combine the low-sodium soy sauce, freshly grated ginger, vegetable oil, cornstarch, and baking soda. Marinate the beef for at least 30 minutes. This not only infuses flavor but also tenderizes the meat.

In another bowl, whisk together the ingredients for the sauce: ground white pepper, salt, light soy sauce, rice vinegar, oyster sauce, toasted sesame oil, dark soy sauce, and sugar. This combination ensures a well-rounded flavor.

While the beef is marinating, prepare your vegetables. Julienne the carrot, slice the bell pepper, and chop the scallions while also separating the green and white parts. This little touch adds a visual appeal to the dish.

Heat a tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Once hot, add the marinated beef, stir-frying it until it’s just browned, about 2-3 minutes. You want it to be tender, not overcooked.

Add the white parts of the scallions, carrot, bell pepper, mushrooms, Napa cabbage, and bamboo shoots to the skillet with the beef. Stir-fry for 3-4 minutes until the vegetables become tender yet still crisp.

Once the vegetables have softened slightly, push everything to the side of the skillet. If necessary, add a little more oil, then toss in your lo mein noodles. Pour the prepared sauce over the noodles and mix everything thoroughly. Ensure the noodles are coated evenly.

Finally, add the mung bean sprouts and snap peas. Stir-fry for an additional minute until everything is heated through. Sprinkle in the green parts of the scallions for a fresh finish.