Step 1

Batter the beef: Cut the flank steak into 1/4" thin strips, slicing against the grain. It may help to freeze the meat for 10-20 minutes before slicing. Whisk the cornstarch, flour, and white pepper together in a mixing bowl. Add the water and egg and whisk until the batter is smooth. Toss the beef strips in with the batter to coat.

Step 2

Fry the beef: Add the vegetable oil to a pot, filling it 2-3 inches with the oil. Heat the oil to 350F. Add the beef strips, working in batches, and use a fork to stir and break them apart as they cook. Fry for 3-4 minutes, or until golden brown. Remove the beef strips with a slotted spoon and let them drain on a paper towel lined plate.

Step 3

Cook the sauce: Whisk the sauce ingredients together in a bowl. Heat the sesame oil in a large skillet over medium-high heat. Add the garlic and ginger, and cook for 1 minute or until fragrant. Add the sauce to the skillet and let it bubble, while stirring, for 1-2 minutes until slightly thickened.

Step 4

Finish: Add the fried beef strips to the skillet and toss to coat well in the sauce. Cook for another 1-2 minutes until the sauce is thickened and fully coats each beef strip. Garnish with sesame seeds and green onion.