Cut the beef, across its grain, into slices. Then put them into a bowl.
Add baking soda, salt, cornstarch, light soy sauce and water. Stir and rub with your hand until the liquid is fully absorbed by the meat. Add oil and give a final rub to distribute it evenly. Leave to marinate for 15 minutes (refrigerate if left longer).
Prepare the sauce
In a small bowl, mix oyster sauce, Shaoxing rice wine, light soy sauce, dark soy sauce, cornstarch, sugar, white pepper, sesame oil and water. Set aside.
Blanch the broccoli
Cut broccoli into bite-sized pieces (including the stem part). Bring water to a full boil in a wok. Blanch the broccoli for 1 to 1½ minutes depending on your preference.
If using a skillet (frying pan), make sure the water is covering half the height of the broccoli florets. Cover with a lid so that the steam will gather and cook the top part of the broccoli.
Sear the beef
Wipe dry and heat the wok/skillet over medium-high heat. Pour in 1½ tablespoons of oil. Add the marinated beef. Distribute the pieces in a single layer to sear evenly.
Once lightly brown on the side touching the wok/skillet, flip and stir-fry for a further 30 seconds or so until the meat loses its pinkness on the surface (do not overcook). Transfer the beef and its cooking liquid to a bowl/plate. Side aside.
Combine the dish
Add the remaining ½ tablespoon of oil to the wok/pan. Stir-fry minced garlic and ginger until fragrant.
Turn the heat to medium-low and pour in the sauce mixture (remember to stir it well beforehand in case any starch sinks to the bottom).
Add the broccoli and the beef. Stir around while the sauce thickens. Dish out when it reaches your preferred consistency (bear in mind that it will become a little thicker as the dish cools).
Notes
You can add other crunchy vegetables (or replace broccoli altogether) to this recipe, such as celery, bell peppers, mushrooms, snow peas (mangetout), snap peas, zucchini (courgette), Gai Lan (Chinese broccoli), asparagus, onion, etc.