Marinate the Beef: Combine thinly sliced flank steak with soy sauce, cornstarch, and rice wine in a bowl. Toss to coat and marinate for at least 15 minutes.

Prepare the Sauce: Whisk together oyster sauce, hoisin sauce, chili garlic sauce, brown sugar, and rice vinegar until well blended. Set aside.

Cook the Noodles: Bring a large pot of salted water to a boil and cook egg noodles according to packaging instructions until tender, about 4-6 minutes. Drain and rinse under cold water.

Stir-Fry the Beef: Heat a large skillet over medium-high heat, add oil, and then the marinated beef. Sear for about 3-4 minutes until browned.

Add the Vegetables: Toss in mixed vegetables and stir-fry for another 2-3 minutes until vibrant and tender.

Combine Everything: Pour the sauce over beef and vegetables, stir to coat, then add rinsed noodles, tossing until heated through.

Serve and Garnish: Transfer to plates and garnish with green onions or sesame seeds. Serve warm.