First Step: Tenderize and marinate the beef Coat the thinly sliced beef in baking soda and refrigerate for 30 minutes to 1 hour to tenderize the meat using the velveting method. Afterward, rinse the beef thoroughly under cold water, drain, and pat dry. Then, marinate the beef with light soy sauce, dark soy sauce, oyster sauce, Shaoxing wine, and toasted sesame oil. Allow it to rest for at least 1 hour; longer marinating up to 24 hours benefits tougher cuts.

Second Step: Prepare the black beans and sauce Soak the preserved salted fermented black beans in water for 30 minutes to 1 hour to reduce excessive saltiness. Drain well, lightly mash about three-quarters of the beans with a fork while leaving some whole for texture. Combine light soy sauce, dark soy sauce, oyster sauce, sugar, and stock or water in a bowl. Separately, mix the cornflour slurry (cornflour with water) to be added later to thicken the sauce.

Third Step: Stir-fry beef and vegetables Heat the vegetable oil in a wok or large skillet over high heat. Shallow fry the marinated beef in batches for 2 to 3 minutes until browned but not completely cooked. Remove beef and drain most of the oil, leaving about 3 tablespoons in the pan. Add the soaked black beans, stir-frying for about 20 seconds, then add minced garlic and ginger for 10 seconds until fragrant. Add onion and capsicum, stir-frying 2 to 3 minutes until vegetables are tender-crisp.

Fourth Step: Combine beef and sauce Return the beef to the wok. Pour Shaoxing wine down the sides of the pan to cook off alcohol and deepen the flavor. Stir the sauce mixture and pour it along with the cornflour slurry into the wok. Cook briefly, stirring constantly until the sauce thickens, becomes glossy, and coats the beef and vegetables evenly. Taste and adjust seasoning if needed.

Final Step: Serve and garnish Serve the beef in black bean sauce hot over steamed rice. Garnish with sliced spring onions and sprinkle toasted sesame seeds if desired for extra aroma and texture. For dietary adaptations, replace beef with tofu and adjust cooking times accordingly.