Begin by boiling water in a large pot. Add the chow mein egg noodles, letting them soak for 30 seconds to 1 minute until soft but not mushy. Once they’ve softened, drain them well and set aside.

In a small bowl, combine dark soy sauce, regular soy sauce, oyster sauce, fish sauce, sugar, and water. Whisk the mixture until the sugar fully dissolves.

Heat 1 tablespoon of corn oil in a wok over medium-high heat. Add the yellow onion and white parts of the green onions, sautéing them for about 1 minute until fragrant.

In the same wok, add another tablespoon of oil and let it heat up. Spread the soaked chow mein noodles into a thin, even layer, allowing them to cook for 2 minutes until they start to crisp up.

Lower the heat slightly and add the cooked onions, remaining green onions, and bean sprouts to the crispy noodles in the wok. Pour in the prepared sauce, stirring gently to combine all the ingredients.

Finally, drizzle the stir-fry with sesame oil and toss everything together. Serve your delicious Cantonese chow mein immediately while it’s still hot and crispy.