Beef and Pepper Stir Fry (from The Woks of Life)

For the beef and marinade:
12 oz. flank steak, sliced into thin strips
1⁄4 teaspoon baking soda (optional tenderizer)
​2 teaspoons soy sauce
1⁄2 teaspoon sesame oil
1 tablespoon cornstarch
1 teaspoon oil
For the rest of the dish:
2 tablespoons oil
3 cloves garlic, sliced
2 green peppers, de-seeded and julienned to 3-inch strips
1 long red or green chile, de-seeded and julienned to 3-inch strips
1 tablespoon Shaoxing wine
1⁄2 teaspoon salt
1⁄2 teaspoon sugar
1 tablespoon soy sauce
1 teaspoon dark soy sauce Fresh ground white pepper
1⁄4 cup chicken stock (optional)

Add all the marinade ingredients to the beef in a bowl, mix well and set aside for 30 minutes at room temperature. When you're ready to cook, add oil to a wok and place over high heat until it's almost smoking. Sear the beef until it's just browned but still a little rare. If your wok is as hot as it should be, the beef should not stick and you should see a nice seared color. Turn off the heat while you transfer the beef to a separate bowl. Leave any oil/fat in the wok.
Heat the wok back up to medium-high heat and add the garlic and peppers. Stir-fry for 20 seconds and then spread the wine around the wok to de-glaze it. Stir-fry for another 20 seconds and add the beef back to the wok along with any juices from the bowl. Add salt, sugar, soy sauces and fresh ground pepper. Turn the heat back up to high and stir-fry for another 1 to 2 minutes, or until the peppers turn darker.
If you like to have more sauce with the dish, add the chicken stock to further de-glaze the wok and reduce the liquid slightly. The cornstarch from the marinade will help thicken the sauce. Plate and serve immediately with rice.