Start by bringing a pot of water to a rolling boil. Add the chow mein egg noodles and soak them for 30 seconds to 1 minute, just until they soften but don’t overcook. Drain the noodles in a colander, giving them a gentle shake to remove excess water, then set aside.

In a small bowl, combine the dark soy sauce, regular soy sauce, oyster sauce, fish sauce, granulated sugar, and water. Stir the mixture well until the sugar completely dissolves, creating a flavorful sauce that will coat your Cantonese chow mein beautifully.

Heat 1 tablespoon of corn oil in a wok over medium-high heat until it shimmers. Add the sliced yellow onion and the white parts of the green onions, sautéing them for about 1 minute until they become fragrant and tender. Transfer the sautéed mix to a plate and set it aside.

In the same wok, add another tablespoon of corn oil over medium-high heat. Spread the soaked chow mein noodles evenly in the wok and let them cook undisturbed for about 2 minutes, allowing them to develop a crispy base. Flip the noodles with a spatula, add another tablespoon of oil, and cook for another 2 minutes until both sides are golden and slightly charred.

Lower the heat slightly, then add the sautéed onions, green onions, and fresh bean sprouts to the crispy noodles. Pour in the prepared sauce and gently toss everything together for 1-2 minutes until the noodles and veggies are evenly coated with a glossy glaze.

Remove the wok from heat and drizzle a small amount of sesame oil over the noodle mixture. Toss it one last time to distribute the nutty fragrance evenly. Serve the Cantonese chow mein hot, garnished with the green onion tops if desired, and enjoy.