Quarter the quails,removing backbones and wing tips. Clean insides,pat dry with paper towel.
Dry-roast salt and Sichuan peppercorns in a heavy-based pan. When peppercorns begin to"pop"and become aromatic,take off the heat. Allow to cool,then grind to a powder using a mortar and pestle or a spice grinder.
Mix the Sichuan salt mix with the sugar,soy sauce and Shaoxing until the sugar dissolves. Add the quail pieces,toss together and marinate overnight.
Heat the oil in a wok or deepfryer until just smoking (180°C on a thermometer). Coat each quail piece in flour,shaking away any excess,and deep-fry in batches until golden brown (about 5-8 minutes each). Remove from the wok and drain on a paper towel.
For the cabbage,clean the wok and reheat until just smoking. Add the peanut oil and,when hot,stir-fry the ginger and garlic until fragrant. Add the cabbage,stir-fry for one minute,then deglaze the wok with the Shaoxing. Add the black vinegar,white vinegar,palm sugar and oyster sauce and cook for another minute.
Spoon the cabbage onto a large serving plate. Arrange the quail pieces on top and sprinkle with the combined spring onion,coriander,chilli and garlic. Serve with chilli sauce on the side.