Making 30-Minute Mongolian Beef is quick and straightforward. Just follow these easy steps:

1. Prep the Beef: Slice the flank steak against the grain into thin strips, about ¼ inch thick. This ensures tenderness.
2. Heat the Oil: In a large skillet or wok, heat the vegetable oil over medium-high heat until it’s shimmering.
3. Cook the Beef: Add the sliced beef to the skillet in a single layer. Let it sear without stirring for about 2-3 minutes. Then, stir-fry for an additional 2-3 minutes until browned and cooked through. Remove the beef from the skillet and set aside.
4. Make the Sauce: In the same skillet, combine soy sauce, brown sugar, minced garlic, and minced ginger. Stir until the sugar dissolves, creating a sweet and savory sauce.
5. Thicken the Sauce: In a small bowl, mix cornstarch and water to make a slurry. Add this to the sauce and stir continuously for about 1-2 minutes until the sauce thickens.
6. Combine: Return the beef to the skillet and toss until the beef is fully coated with the sauce. Cook for an additional minute to heat through.
7. Garnish: Remove from heat and sprinkle sliced green onions on top before serving.
8. Serve: Plate the Mongolian beef over cooked rice or noodles.

These straightforward steps will help you create a dish that not only tastes amazing but also looks fantastic on the plate.