1poundregular or soft tofu(450g, cut into 2-inch squares, 1/2-inch thick)
1tablespooncornstarch(mixed with 1 tablespoon of water)
For the beef & marinade, combine the beef, water, vegetable oil, cornstarch, baking soda, and soy sauce in a medium bowl. Let the beef marinate for 20 minutes.
Heat the wok until smoking and spread 2 tablespoons of oil around the perimeter. Sear the beef for 20 seconds on each side. You want the beef seared on the outside and about 80% done. Remove from the wok and set aside.
Add the ginger, and caramelize for 20 seconds. There should be oil in the wok from searing the beef, but add another tablespoon of oil if needed. Next, add the minced garlic and the white portion of the scallions. Stir fry for 10 seconds, and add the Shaoxing wine.
Stir again for 10 seconds, and add the chicken stock, oyster sauce, soy sauce, sesame oil, white pepper, and sugar. Stir-fry until combined, and then gently slide the tofu into the wok. Be careful––the pieces are delicate and will break up easily without proper handling!
Let the tofu and the sauce come up to a boil, and drop in the green portions of the scallions and the seared beef, including any juices.
While everything is coming up to a boil, mix your cornstarch slurry. Check the seasoning of the sauce, and add more salt or soy sauce if desired, but remember it will get saltier after it thickens!
Carefully stir in the cornstarch slurry, and lower the heat to medium as the sauce thickens. Be as gentle as possible when stirring so as to minimize tofu breakage. A pushing/stirring motion to rotate the mixture around the wok usually works best. Adjust the thickness of the sauce by adding more cornstarch slurry or chicken stock until it is to your liking. Serve over steamed rice!