Mongolian Beef Recipe step by step guide

Name: Mongolian Beef Recipe
Prep time: 15 min
Cook time: 15 min
Total time: 30 min
Yield: 4 servings
Cuisine: Chinese-American
Ingredients: 1 pound flank steak (thinly sliced against the grain); 1/4 cup cornstarch; 3 tablespoons vegetable oil (divided); 1/2 cup low-sodium soy sauce; 1/2 cup brown sugar; 1/4 cup water; 1 teaspoon minced ginger; 3 cloves garlic (minced); Pinch of red pepper flakes (optional for heat); 4 green onions (sliced)