In a medium bowl, toss the sliced beef with 1 tablespoon soy sauce, 1 teaspoon sesame oil, and 1 tablespoon cornstarch. Let it marinate for 10-15 minutes while you prepare the other ingredients.

In a small bowl, whisk together the sauce ingredients: light soy sauce, dark soy sauce, oyster sauce, sesame oil, sugar, minced garlic, and grated ginger. Set aside.

Cook the noodles according to package instructions until al dente. Drain, rinse with cold water to stop cooking, and toss with a teaspoon of oil to prevent sticking.

Heat 1 tablespoon of vegetable oil in a wok or large skillet over high heat. Add the marinated beef in a single layer. Sear for 1-2 minutes per side until browned. Remove beef from the pan and set aside.

Add another tablespoon of oil to the pan. Add the onions and carrots, stir-frying for 2 minutes. Add the broccoli and a splash of water, cover, and steam for 1 minute until veggies are tender-crisp.

Return the beef to the pan. Add the cooked noodles and the prepared sauce.

Toss everything together continuously for 1-2 minutes until the noodles are evenly coated in the sauce and heated through.

Garnish with sesame seeds and chopped green onions. Serve immediately.