In a bowl, combine sliced beef with soy sauce, cornstarch, and sesame oil. Mix well and let marinate for 10 minutes.

Cook the egg noodles according to package instructions. Drain and set aside.

Heat 1 tablespoon of vegetable oil in a wok over medium-high heat. Add garlic and stir-fry for 30 seconds.

Add bell pepper, broccoli, and carrots. Stir-fry for about 3-4 minutes until vegetables are tender-crisp.

Push the vegetables to the side of the wok and add the marinated beef. Stir-fry until the beef is browned and cooked through, about 4-5 minutes.

Add the cooked noodles and sauce ingredients to the wok. Toss everything together and stir-fry for another 2-3 minutes until well combined.

Remove from heat and serve hot, garnished with sesame seeds if desired.