Cut the steak into strips if not already cut. Then evenly coat the steak with the cornstarch. To do this I put both in a gallon sized ziplock bag and shook it until it was covered.
In a separate bowl, Combine garlic, soy sauce, ginger, brown sugar, water, half the green onion. Set aside.
Heat vegetable oil in a pan, then add in the steak. Fry the steak strips on high heat until the edges crisp. Once crisped, remove the steak from the plan.
Pour the sauce mixture into the pan used to cook the steak. Cook until boiling, then add in the steak and let it return to a simmer for about 7 mins or until sauce thickens.
Slice the green onion sprinkle on top as a garnish