Chinese Pepper Steak

1 pound beef top sirloin steak

¼ cup soy sauce

2 tablespoons white sugar

2 tablespoons cornstarch

½ teaspoon ground ginger

3 tablespoons vegetable oil, divided

1 red onion, cut into 1-inch squares

1 green bell pepper, cut into 1-inch squares

2 tomatoes, cut into wedges

Slice steak into 1/2-inch thick slices across the grain.

Whisk together soy sauce, sugar, cornstarch, and ginger in a bowl until the sugar has dissolved and the mixture is smooth. Place steak slices into the marinade, and stir until well-coated.