01 - Cook chow mein noodles according to package directions. Drain thoroughly and rinse under cold running water to stop cooking process.
02 - Heat 1 tablespoon vegetable oil in a large nonstick skillet or wok over medium-high heat. Spread cooked noodles in an even layer. Fry undisturbed for 4-5 minutes until bottom becomes golden and crispy. Flip carefully and crisp opposite side for 2-3 minutes. Transfer to a plate and reserve.
03 - Whisk together soy sauce, oyster sauce, hoisin sauce, sesame oil, sugar, garlic, ginger, water, and cornstarch in a small bowl until cornstarch dissolves completely.
04 - Wipe out skillet. Heat remaining 1 tablespoon oil over high heat. Add onions and carrots; stir-fry for 2 minutes. Add bell pepper, mushrooms, and snow peas; stir-fry for 3-4 minutes until vegetables become tender-crisp and maintain vibrant color.
05 - Pour sauce mixture into skillet with vegetables. Stir constantly for 1 minute as sauce bubbles and thickens to coat vegetables evenly.
06 - Stir in bean sprouts and half the spring onions. Toss quickly to combine and heat through, about 30 seconds.
07 - Arrange crispy noodles on serving platter. Top with stir-fried vegetables and thickened sauce. Garnish with remaining spring onions, sesame seeds, and coriander if using. Serve immediately while noodles remain crispy.