1.Shell and devein prawns, leaving tails intact. Cut squid hoods in half. Score inside surface of each piece; cut into 5cm-wide strips. Cut fish into 3cm pieces.
2.Heat half of the oil in wok; stir-fry seafood, in batches, until lightly browned all over and cooked through. Heat remaining oil in wok; stir-fry onion, garlic and ginger until onion softens.
3.Return seafood to wok. Add bok choy, choy sum and combined sauces; stir-fry until greens are just wilted and heated through.