Stir together all marinade ingredients and add chicken, stirring until well coated. Marinate at room temperature if it's not too hot for about 10 minutes or longer if in the fridge.
Place the Sichuan peppercorns and corn flour into the Thermomix bowl and mill 10 sec/speed 8.
Add garlic, ginger, vinegar, tamari, hoisin, sesame oil and sugar to the Thermomix bowl and blend 10 sec/speed 6.
Heat the EVOO in a wok over a high heat until just smoking. Add the dried chilies, they will be quite strong, so make sure you are ready for that! This will only be a matter of seconds.
Add the marinated chicken, stir frying until there is no pink, at least 3 minutes.
Pour over the sauce and add a few of the spring onions, reserving some for garnish. Add the peanuts and cook for another 2-3 minutes.
Serve immediately with or without steamed rice and plenty of sliced fresh spring onions.