Add the thinly sliced flank steak to a gallon-size Ziplock bag, drizzle with 2 Tablespoons Tamari, sprinkle on 2 Tablespoons cornstarch, and season with salt and pepper. Seal the bag and squish to coat evenly. Refrigerate for up to an hour.

Whisk 2 Tablespoons cornstarch with half the water in a small bowl. Add 1/3 cup Tamari and whisk again to combine.

Steam 12 oz broccoli florets in a steamer basket over boiling water for 5-7 minutes until tender.

Heat 2 teaspoons oil in a large wok over high heat. Sear 1/3 of the beef until deep golden brown, then stir-fry until just cooked through. Remove to a plate.

Heat 1 teaspoon oil and repeat searing and stir-frying with another 1/3 of the beef. Remove to the plate.

Heat the remaining 1 teaspoon oil and sear and stir-fry the last batch of beef. Remove to the plate.

Return the pan to medium heat. Whisk the sauce again, then add to the pan. Stir for 1 minute until slightly thickened, then add the beef and cook for 1-2 more minutes until the sauce is fully thickened.