Creating Mongolian Beef and Noodle is easy if you follow these steps:

1. Prepare the Beef: In a bowl, combine the sliced flank steak with 2 tablespoons of soy sauce. Marinate for about 10 minutes.
2. Coat the Beef: Sprinkle cornstarch over the marinated beef and toss until evenly coated.
3. Heat the Pan: In a large skillet or wok, heat 2 tablespoons of vegetable oil over medium-high heat.
4. Cook the Beef: Add the beef to the skillet in a single layer. Cook for about 2-3 minutes until browned. Remove from the skillet and set aside.
5. Sauté Aromatics: In the same skillet, add the remaining tablespoon of oil. Add minced garlic and ginger, sautéing for 30 seconds until fragrant.
6. Prepare the Sauce: In a small bowl, whisk together 1/2 cup soy sauce, brown sugar, sesame oil, and red pepper flakes (if using).
7. Combine Ingredients: Return the beef to the skillet. Pour the sauce over the beef and stir well to coat.
8. Simmer: Allow the mixture to simmer for about 5-7 minutes until the sauce thickens slightly.
9. Add Noodles: Add the cooked noodles to the skillet, tossing everything together until well combined and heated through.
10. Garnish: Stir in the chopped green onions and top with sesame seeds if desired.

By following these steps, you’ll create a delicious dish that is sure to impress!