Step 1

Heat the sesame and vegetable oils in a large skillet over medium heat.

Step 2

Meanwhile, slice the flank steak into thin slices, approximately ¼ of an inch thick.

Step 3

Place the sliced steak and the cornstarch in a large bowl. Toss gently to coat the strips.

Step 4

In a small bowl, whisk together the soy sauce, water, brown sugar, ginger, and red pepper flakes.

Step 5

Place the steak in a single layer in the hot oil and cook for 1 minute. Flip and cook for an additional minute. The edges of the steak should be begin to get brown as it cooks. Remove the steak from the pan.

Step 6

Add the garlic to the pan and cook for 30 seconds, stirring constantly to prevent burning.

Step 7

Pour the soy sauce mixture into the skillet and bring to a boil. Cook for 3 to 4 minutes, or until the mixture is reduced by half. Add the steak back to the skillet and cook for an additional 2 minutes. Stir in the green onions.

Step 8

Serve while warm, ideally alongside rice to soak up the sauce.