Prep Your Vegetables: Slice up the onion, carrots, cabbage, garlic, and green onions, keeping them separate since they'll go in at different times. Having everything ready before you start cooking is essential for this quick-cooking dish.

Make the Sauce: In a small bowl, stir together the dark soy sauce, regular soy sauce, brown sugar, water, sesame oil, cornstarch, white pepper, and oyster sauce until the sugar dissolves and there aren't any cornstarch lumps. This flavorful blend is the signature taste of lo mein.

Cook the Noodles: Bring a pot of water to a boil and cook your egg noodles for about 5 minutes (or follow package directions). Once they're just tender, drain and rinse under cold water to stop the cooking process and prevent them from becoming mushy during stir-frying.

Stir-Fry the Vegetables: Heat a wok or large skillet over high heat until very hot. Add a splash of oil, then add the garlic, carrots, and onion. Stir-fry for 2 minutes, constantly moving the ingredients. Add the cabbage and continue stir-frying for another 2 minutes until everything starts to soften but still maintains some crunch.

Combine Everything: Add your cooked noodles to the pan along with the sauce and green onions. Keep stirring for about a minute until the noodles are hot and completely coated in the glossy sauce, which should thicken and cling to all ingredients.

Serve Immediately: Transfer your homemade lo mein to serving plates while hot. The noodles should be perfectly coated with the shiny sauce and the vegetables should retain some of their texture and brightness.