Put the sliced beef in a bowl with the soy sauce, 1 tsp cornstarch, baking soda, sugar and 1 tbsp water. Mix with your hand for about a minute until the liquid disappears into the meat, then stir in 2 tsp oil. Leave it for at least 10 minutes while you do everything else.
Crack the eggs into a bowl. Add the salt, white pepper, the cornstarch slurry and the sesame oil. Beat with chopsticks or a fork until just combined. You want streaks of white gone but not a frothy, over-beaten mixture.
Heat 1 tbsp of the cooking oil in a wok or large nonstick skillet over high heat until it shimmers. Add the beef in a single layer and leave it alone for 45 seconds. Toss, add the scallion whites and the Shaoxing wine if using, and stir fry for another 45 to 60 seconds until the beef is just cooked through with a little pink at the center of the thicker pieces. Tip the beef and any juices into the egg mixture and stir once.
Wipe the pan if there is anything burnt on it, then add the remaining 1/2 tbsp oil and put it back over medium heat. When the oil is hot but not smoking, pour in the egg and beef mixture all at once.
Wait 10 seconds for the bottom to set, then push the set egg from the edge toward the center with a spatula, letting the raw egg run into the gap. Keep doing this in slow, big strokes for about 60 to 90 seconds. Pull the pan off the heat while the top still looks wet and glossy. It will finish setting on the plate.
Slide onto a plate, scatter the scallion greens over the top and serve straight away with rice.