Blanch the pork in boiling water for 5 minutes. Drain and pat dry. Rub the pork with rice wine and soy sauce then let sit for 10 minutes.
Heat the oil in a wok until hot. Place the pork belly skin-side down and fry over low heat for 3 minutes or until the skin turns dark red. Remove from the wok.
Place the pork belly in a large saucepan of simmering water (80 degrees C) and simmer over low heat for 30 minutes or until the skin becomes soft. (Maintain the temperature at 80 degrees C).
Cut the pork into 10x1cm slices then cut across the length, keeping the skin connected. Arrange the pork slices skin-side down in a heat-proof bowl. Sprinkle evenly with black beans, chicken stock powder and salt.
Steam over high heat for at least 25 minutes. Remove from the steamer. Cover the bowl with a serving dish and invert - the pork should be skin-side up now.
Spoon the steaming juice into a small saucepan then add 1/2 teaspoon cornflour and cook until the sauce has thickened. Drizzle over the pork and garnish with spring onion and serve.
Black bean paste and Shaoxing wine can be purchased in Asian speciality shops or online.