Rinse the chicken inside and out and pat dry with paper towel. Rub the salt and five-spice powder into the skin and leave for 20 minutes. Heat the oil in a wok or deep-fryer until just smoking (180°C/350°F), and deep-fry the whole chicken for 8 minutes, until the skin turns golden. Remove and leave to cool.
Put the bird on a chopping board and cut out the backbone, then push down to flatten slightly and put on a deep, round plate.
Mix together the ginger, spring onions, soy sauce, shaoxing, peanut oil and extra sea salt and pour over the chicken, rubbing into the skin. Put in a steamer over a pot or a wok of rapidly boiling water, cover and steam for 20 minutes, or until cooked through.
For the spicy dipping sauce, pound the chillies, garlic, coriander roots, ginger and sea salt in a mortar with a pestle to form a paste. Heat the oil until just smoking and carefully pour the hot oil over the sauce, then mix together. To serve, shred the chicken meat into large pieces. Put on a plate, skin-side-up, pour the juices over, sprinkle with coriander and serve with the dipping sauce.