RUB THE FISH FILLETS with salt and cornstarch. Heat a wok or large frying pan until it is hot, then add the oil. Brown the fish on each side until it is golden brown. Remove the fish and drain on kitchen paper. Drain off all but 1 tablespoon of oil, add the garlic and ginger and stir-fry for 20 seconds. Add the sauce ingredients, and cook for 3 minutes or until the garlic is tender. Return the fish to the wok and reheat through. Serve at once with the garlic cloves.