Arrange beef in a large bowl. Season with salt and pepper. Add cornstrach. Mix well. Let it stay for 10 minutes.
Heat a pan and then pour cooking oil. Let the oil heat up to 350F. Fry the beef coated with cornstrach for 1 minute per side. Remove from the pan and then place on a wire rack or a plate lined with paper towel. Note: Excess oil needs to be separated from the beef. The wire rack will allow the oil to drip, while paper towels absorb it.
Prepare the sauce by sautéing garlic and ginger in a pan using 3 tablespoons of oil. Once the garlic starts to brown, pour soy sauce and add Hoisin sauce. Stir. Add brown sugar and water. Stir and let boil.
Make the sauce thicker by combining 1 tablespoon of cornstarch with 4 tablespoons water. Stir until sauce thickens.
Add fried beef into the pan. Toss.
Add scallions. Continue to cook in low heat for 2 minutes while tossing.
Transfer to a serving plate. Share and enjoy!