Step 1

In a 2-cup measuring cup or small bowl, whisk together the sauce ingredients; set aside.

Step 2

Heat 1 teaspoon of the vegetable oil in a 12-inch skillet over medium-high heat. Add the sliced peppers, season with salt and pepper, and saute for 3 to 5 minutes, until just tender. Remove from the skillet to a plate and set aside.

Step 3

Add the remaining 2 teaspoons of oil to the skillet, increase the heat to high, and add the flank steak. Sprinkle with the garlic powder and season with salt and pepper. Cook, tossing occasionally until cooked through, about 5 minutes.

Step 4

Return the peppers to the pan with the steak and reduce heat to medium. Whisk the sauce ingredients again and pour over the steak and peppers mixture. Simmer for 2 to 3 minutes, stirring occasionally, until sauce thickens. Serve with white rice.