1.Holding crab firmly, slide sharp knife under top of shell at back; lever off shell. Remove and discard gills and mustard-coloured gut. Rinse crab body under cold running water; quarter crab. Remove claws; using nutcracker or meat mallet, crack both sections of claws.
2.Heat oil in wok or large frying pan; stir-fry garlic, ginger and chilli until fragrant. Add sauces, sugar, stock and the water; bring to a boil. Boil, stirring constantly, for 5 minutes, then place two-thirds of the sauce in medium heatproof jug; reserve.
3.Place claws in wok with remaining sauce; stir-fry about 4 minutes or until changed in colour. Remove from wok; cover to keep warm. Place half of the reserved sauce and half of the crab body pieces in wok; stir-fry about 5 minutes or until changed in colour. Remove from wok; cover to keep warm. Repeat with remaining reserved sauce and crab body pieces.
4.Serve crab immediately, sprinkled with coriander