Place the sliced flank steak in a bowl and coat it evenly with cornstarch. This helps to tenderize the meat and create a crispy texture when cooked.
Heat the Vegetable Oil:
In a wok or a large skillet, heat the vegetable oil over medium-high heat. Ensure the oil is hot before adding the beef.
Sear the Beef:
Add the cornstarch-coated flank steak to the hot oil, spreading it out to ensure even cooking. Sear the beef on both sides until it becomes brown and crispy. This should take about 2-3 minutes per side. Once done, remove the beef from the pan and set it aside.
Add soy sauce, water, and brown sugar to the pan. Stir the mixture well to combine. Allow the sauce to simmer and thicken for about 2-3 minutes.
Combine Beef and Sauce:
Return the seared beef to the pan, coating it evenly with the sauce. Let it simmer for an additional 2-3 minutes, allowing the flavors to meld.
Garnish and Serve:
Once the sauce has thickened and the beef is fully coated, sprinkle sliced green onions on top. For an extra touch, add sesame seeds for garnish.
Serve Hot:
Plate the Panda Express Mongolian Beef over steamed rice or noodles. Ensure to spoon some of the delicious sauce over the beef. Serve hot and enjoy the rich, savory flavors.