Cook the noodles according to package instructions, then rinse under cold water and drain thoroughly.
Heat 1 tablespoon vegetable oil in a nonstick or cast iron skillet over medium-high heat. Add the noodles and press them into an even layer. Let cook undisturbed for 5-7 minutes until the bottom is golden and crispy. Flip (or divide and flip in sections) and crisp the other side for 3-5 minutes. Transfer to a serving plate.
In another pan, heat 1 tablespoon oil. Sauté garlic and onion for 1-2 minutes until fragrant.
Add bell peppers, carrots, mushrooms, and bok choy. Stir-fry for 3-4 minutes until vegetables are just tender.
Add the cooked protein and toss to combine.
In a small bowl, whisk together soy sauce, oyster sauce substitute, sesame oil, sugar, cornstarch, and broth. Pour into the pan with vegetables and meat. Stir and cook until sauce thickens, about 2 minutes.
Pour the stir-fry mixture over the crispy noodles and serve immediately.