Prepare all the ingredients before you start cooking, as stir-frying is quick.
Heat the groundnut oil in a wok over high heat until hot and just beginning to smoke.
Add the sliced onion, ginger and carrot. Stir-fry for about 2 minutes, keeping everything moving so it cooks evenly.
Add the garlic, pak choi, bean sprouts and crushed Sichuan pepper. Stir-fry for another minute.
Pour in the rice wine, soy sauce and rice vinegar. Toss well, then cover with a lid and reduce the heat slightly. Cook for about 3 minutes, until the pak choi has just wilted but still retains some crunch.
Add the raw prawns, cover again and cook for 2–3 minutes, until the prawns turn pink and opaque. If using pre-cooked prawns, simply stir them in and warm through briefly to avoid overcooking.
Finish by stirring in the sesame oil.
Serve immediately, scattered with fresh coriander leaves, alongside noodles or steamed rice.