Increase the pan heat to high, add 2 tablespoons of vegetable oil, and sear the marinated beef strips for 2-3 minutes until browned and cooked through.
In a bowl, whisk together 2 tablespoons of soy sauce, hoisin sauce, rice vinegar, and cornstarch. Pour this sauce over the cooked beef and let simmer for 2-3 minutes until thickened.