1.Combine fish and stock in medium saucepan, bring to the boil. Reduce heat, simmer 1 minute. Remove from heat. Stand, covered, 10 minutes.
2.Meanwhile, combine sauce, vinegar, oil and sugar in large bowl. Add watercress, sprouts, wombok, onion and chilli, mix gently.
3.Drain fish, remove skin, flake fish over salad.
Brown rice vinegar, made from brown rice, has been called the eastern version of apple cider vinegar, although its mild flavour has a subtle sweetness and about half the sharpness. It is available from Asian grocery stores and some health-food stores