2 tbsp Chinese black rice vinegar or cider vinegar
2 tsp sugar
Dust the fish fillets with cornflour, shaking off any excess. Heat a wok until it is very hot. Add the oil and fry the fish gently for 2-3 minutes until golden brown. Drain the cooked fish on kitchen paper.
Pour off all the oil. Wipe the wok and reheat. Add all the hot and sour sauce ingredients, bring to a boil then simmer. Add the fish and simmer in the sauce for two minutes. Serve on a warm platter.