Velvet beef - Place the Beef Rump Steak in a bowl. Sprinkle with Baking Soda and use your fingers to toss the beef to coat as evenly as possible. Set aside for 20 minutes (no longer).
Rinse the beef under tap water in a colander to remove the baking soda. Shake and pat off excess water (doesn't need to be fully dry, just not soaking). Return to a clean bowl.
Sauce - Mix Soy Sauce, Oyster Sauce, Chinese Cooking Wine, White Sugar, Sesame Oil and White Pepper together. Measure out 1 1/2 tablespoons of this mixture and use it to coat the beef.
To the remaining sauce, whisk in the Cornstarch until lump-free, then add the Water and stir to combine.
Cook aromatics - Heat the Peanut Oil in a large non-stick pan or wok over high heat. Add the Onion and Garlic and cook for about 10 seconds until fragrant.
Add the beef and stir-fry until it changes colour from red to light brown but is not fully cooked through.
Vegetables #1 - Add the Red Capsicum, Carrots, bok choy stems and white part of the Green Onion. Stir-fry for 1 minute.
Add the prepared sauce, then stir until it starts to bubble and thicken (this will happen quickly).
Leafy vegetables - Add the Bok Choy leaves and green part of the Green Onion. Toss for another 30 seconds to 1 minute until they are just wilted and the sauce is glossy and coats everything nicely.
Serve immediately with rice or cauliflower rice. Garnish with sesame seeds, if desired.
