2 pound flank steak, trimmed
2 medium sized navel Oranges (Original recipe called for 4-6 Pixie tangerines or clementines for every pund of Steak)
2 pound bok choy
6 ounces shiitake mushrooms (I didn’t use this as we have allergies)
4 tablespoons oyster sauce
1 1/2 tablespoons reduced-sodium soy sauce
4 teaspoons rice vinegar ( I used 2 tspn of white wine vinegar as I had only that)
3 teaspoons cornstarch
1/2 teaspoon ground pepper
7 teaspoons peanut oil or canola oil, divided
2 tablespoon finely chopped fresh ginger
8 large cloves garlic, minced
6 scallions, chopped, whites and greens divided
1 Fresno or serrano chile, seeded and thinly sliced (I use Jalapeno as I had only that)
Cut steak in thirds along the grain. Freeze 15 minutes to firm slightly; thinly slice crosswise.
Sliver zest from an Orange to get 1 tablespoon and set aside. To make zest slivers, peel wide strips of the skin from citrus fruit with a vegetable peeler, leaving the white pith behind. Cut the strips into long, thin slivers.
Squeeze enough of the fruit to get 1/2 cup juice. Cut bok choy stems into 1-inch pieces and the leaves into 2-inch pieces. Discard mushroom stems; thinly slice caps.
Whisk the juice, oyster sauce, soy sauce, vinegar, cornstarch and pepper in a small bowl. Place next to the stove.
Heat a 14-inch flat-bottom carbon-steel wok or large skillet over medium-high heat until very hot. Add 2 teaspoons oil and swirl to coat. Add the beef in one layer; cook, without stirring, for 1 minute. Then toss until the beef is no longer pink on the outside, couple of minutes more. Transfer to a plate. If there is more beef, do this in batches.
Add 2 teaspoons oil to the pan; swirl to coat. Add the bok choy stems and mushrooms; stir-fry until the mushrooms release their liquid, about 3 minutes. Add the bok choy leaves; stir-fry until wilted, 1 to 2 minutes. Transfer the bok choy and mushrooms to the plate with the beef.
Add the remaining 1 teaspoon oil, ginger, garlic, scallion whites and chile to the pan and stir-fry for 30 seconds. Add the reserved sauce and heat until bubbling. Return the beef, vegetables and any accumulated liquid to the pan; gently stir until heated through, about 1 minute more. Stir in scallion greens and the reserved zest.