Heat the vegetable oil in a wok until just smoking. Add the mushrooms, mustard greens, radish, ginger and spring onions and stir-fry for 1–2 minutes, or until fragrant, then deglaze the wok with the shaoxing. Add the kecap manis, vinegar, soy sauce, palm sugar and stock. Check for balance, then add the tofu and reduce the heat to very low. Cover with a lid and braise for 4–5 minutes. Carefully transfer to a serving bowl, keeping the tofu intact. Top with the cucumber slices and sprinkle with the Sichuan pepper to serve.