Make the sauce.

Heat 4 tsp vegetable oil in a medium saucepan over medium-low heat. Dont get the oil too hot.

Add ginger and garlic to the pan.

Quickly addthe soy sauce and water before the garlic scorches.

Dissolve the brown sugar in the sauce. Raise the heat to medium and boil the sauce 2-3 minutes or until the sauce thickens a bit. Remove the sauce from the heat after thickening.

Slice the flank steak against the grain into slices of your desired size. Tilt the blade of your knife to about 45° as you slice to get woder cuts.

Dip the steak slices in the cornstarch to apply a dusting to both sides. Let the beef sit about 10 minutes so the cornstarch sticks.

Heat 1 cup of vegetable oil in a wok over medium heat until it is hot, but now smoking.

Add the beef to the oil and sautee for 2 minutes, or just before the beef darkens on the edges. Stir the meat around to ensure even cooking.

Use a slotted spoon to remove the beef from the oil and place on paper towels to drain.

Pour most the oil out of the wok and discard. Place the wok back on a burner over medium heat.

Add meat back to the wok and stir fry for 1 minute.

Add the sauce and the green onions and cook for on last minute, while stirring.

OPTIONAL: thicken the sauce with a cornstarch/water mix and serve with the meal.