Bring a large pot of salted water to a boil. Add the chow mein noodles and cook according to the package instructions—approximately 30 seconds for fresh noodles or 3-4 minutes for dried noodles. Drain the noodles thoroughly and transfer them to a large plate. Allow them to air-dry while preparing the remaining ingredients to achieve a crispier texture during frying.

In a small mixing bowl, combine the white granulated sugar, low-sodium soy sauce, Shaoxing rice wine, oyster sauce, salt, and pepper. Stir well to dissolve the sugar. Set aside 1 tablespoon of this sauce mixture and add it to the thinly sliced beef, along with the baking soda. Mix thoroughly to evenly coat the beef and allow it to marinate while preparing the remaining ingredients.

To the remaining sauce mixture, add the cornstarch and whisk until fully incorporated. This will help thicken the sauce when cooked. Set aside.

Heat ¼ cup of cooking oil in a large non-stick skillet over medium-high heat. Once the oil is hot, carefully add the noodles, spreading them evenly in a circular shape. Allow them to cook undisturbed for 6-8 minutes, occasionally swirling the pan to prevent sticking.

Once the bottom is golden and crispy, carefully slide the noodles onto a clean plate. Place another plate or a large pan lid over the top, and flip the noodles so the crispy side is now facing up.

Add an additional 2-3 tablespoons of cooking oil to the skillet, then slide the noodles back in, crispy side facing up. Pan-fry for another 6-8 minutes, until the second side is equally golden and crisp. Transfer the noodles to a paper towel-lined plate and set aside.

In the same skillet, add 1-2 tablespoons of cooking oil over high heat. Add the sliced onions and mushrooms, allowing them to caramelize for 2-3 minutes, stirring occasionally. Once the onions develop a light char, add the minced garlic and grated ginger. Sauté for 30 seconds, or until fragrant.

Add the marinated beef to the skillet, spreading it evenly. Allow it to sear without stirring for 2-3 minutes, then stir and cook for an additional 1 minute. Add the shrimp and reduce the heat to medium, stir-frying for another 2-3 minutes, or until the shrimp turns pink and opaque. Remove the cooked beef and shrimp from the skillet and set aside.

Pour the prepared sauce mixture and chicken broth into the skillet. Stir continuously and allow it to simmer for 4 minutes, or until the sauce begins to darken and slightly reduce.

Add the optional vegetables—carrots, baby corn, and bok choy—stirring to coat them in the sauce. Simmer for an additional 2-3 minutes, until the vegetables are tender yet still crisp.

Return the cooked beef and shrimp to the skillet. Stir to incorporate and allow the mixture to simmer for 1-2 minutes, until the protein is heated through and the sauce has thickened to the desired consistency.

Carefully pour the stir-fry mixture over the crispy pan-fried noodles. Garnish with sliced green onions and serve immediately.