01 - In a small bowl, whisk together the soy sauce, oyster sauce, hoisin sauce, sesame oil, black pepper, sugar, cornstarch, and water until smooth. Set aside.
02 - Prepare the chow mein noodles according to package directions. Drain, rinse under cold water to halt cooking, and set aside.
03 - Heat 1 tablespoon of vegetable oil in a large wok or skillet over high heat. Add the sliced beef in a single layer and stir-fry for about 2 minutes until just browned on the outside but still tender inside. Remove from the wok and set aside on a plate.
04 - Add the remaining tablespoon of vegetable oil to the wok. Toss in the minced garlic, julienned ginger, and sliced onion. Stir-fry for 1 minute until fragrant and the onion begins to soften.
05 - Add the sliced bell peppers to the wok and stir-fry for 2 to 3 minutes, maintaining a slight crispness and vibrant color.
06 - Return the seared beef to the wok along with the cooked noodles. Pour the prepared sauce over everything and toss vigorously for 2 to 3 minutes until all components are evenly coated and heated through.
07 - Scatter the sliced spring onions over the top. Transfer to serving plates immediately while hot.