Marinate the Beef : In a bowl, combine the beef slices, 30 ml soy sauce, and cornstarch. Toss until evenly coated and let it marinate for 15 minutes while you prepare the other ingredients.

Prepare the Sauce : In a small bowl, mix 30 ml soy sauce, oyster sauce, hoisin sauce, and sesame oil. Set aside.

Cook the Noodles : Cook the lo mein noodles according to the package instructions. Drain and set aside.

Stir-Fry the Beef : Heat 1 tablespoon of vegetable oil in a large skillet or wok over high heat. Add the marinated beef and stir-fry for 2-3 minutes until browned. Remove from the skillet and set aside.

Cook the Vegetables : In the same skillet, add the remaining 1 tablespoon of vegetable oil. Sauté the garlic and ginger until fragrant, about 30 seconds. Add the carrots, bell peppers, and broccoli. Stir-fry for 4-5 minutes until the vegetables are crisp-tender.

Combine and Serve : Return the beef to the skillet and pour in the prepared sauce. Toss to coat everything evenly. Add the cooked noodles and stir-fry for an additional 2 minutes to combine and heat through. Garnish with sliced green onions and adjust the seasoning with salt and pepper to taste.

Serve and Enjoy : Transfer the Beef Lo Mein to a serving dish and enjoy hot, straight from the wok!