Begin by thinly slicing the flank steak against the grain for tenderness. Once sliced, coat the beef pieces evenly in cornstarch; allow to rest for about 10 minutes.

In a medium saucepan over medium heat, add the vegetable oil. Once warm, stir in minced fresh ginger and garlic, sautéing for about 1-2 minutes until aromatic, then whisk in soy sauce, water, and dark brown sugar until dissolved. Let simmer for around 10 minutes.

Heat a skillet over medium-high heat and add enough vegetable oil to coat the bottom. When the oil shimmers, add the flank steak in batches and fry each side for 2-3 minutes until browned and crispy. Remove from skillet and set aside.

Empty excess oil from the skillet, leaving a thin layer, and return the pan to medium heat. Add the fried steak back into the skillet, pour the sauce over the beef, and toss to coat evenly. Stir in sliced green onions, cooking together for 2-3 minutes.

Plate a generous portion of the beef mixture over fluffy cooked rice, drizzled with sauce and garnished with more green onions. Ready to serve!