1/3 cup plus 2 Tablespoons vegetable oil
1 Tablespoon minced garlic
1/2 teaspoon minced fresh ginger
1/2 cup low sodium soy sauce
1/2 cup water
2/3 cup packed dark brown sugar
1 lbs flank steak
1/4 cup cornstarch
3 scallions sliced into 1-inch pieces “only green parts”
Heat 2 tablespoons of vegetable oil in a small pan over medium and low heat. Add the garlic and ginger and fry them until golden brown, about 2 minutes. Add the soy sauce and water and stir.
Stir in the brown sugar and increase the heat to medium. Bring the sauce to boil for 3 minutes. Remove the sauce from the heat and put it aside.
Cut the steak from the side against the grain into 1/4 inch pieces and then throw it together with the corn starch. Put the steak covered pieces on a sieve and shake off the excess cornstarch. Leave the steak to sit for 10 minutes.
Line a plate with paper towels.
Put a large frying pan or wok on medium heat and add 1/3 cup of vegetable oil. Once the oil is hot (but not smoked), add the beef to the pan and fry until it burns on all sides, but badly cooked in the middle, about 2 minutes. Remove the steak from the pan with a skimmer and transfer it to a paper-coated dish. Pour the excess oil out of the frying pan.
Put the frying pan back in medium heat. Add the prepared sauce to the hot pan (it should reach boiling almost immediately), then add the reserved steak and let it boil, stirring continuously, until the sauce has thickened to the consistency of syrup, 3 to 5 minutes. Add the sliced onions and stir. Serve.