Make the sauce. In a thick bottomed pan, pour in the juices. Add the sugar, salt, ginger and chilies. Bring to the boil, lower the heat to medium and simmer, uncovered, until reduced and slightly thickened, about ten minutes. If the sauce is not thick enough for you, disperse a tablespoonful of starch in two tablespoonfuls of water, add to the sauce, stir and continue boiling until thickened. Set aside.
Heat the cooking oil in a wok or frying pan until wisps of smoke start to appear.
In a wide shallow bowl, place about half a cup of starch.
In a mixing bowl, place half a cup of flour, a cup of starch and the ice cubes. Pour in about one-fourth cup of water. Add the chopped herbs. Mix lightly. The batter should not be too thick but thick enough to coat the fish pieces. Add more water if the batter is too thick.
Holding a fish fillet by the edge, dredge in flour then dip in batter until well coated. Carefully drop into the hot oil. Repeat and cook the fish in batches of eight to twelve. This is a very short frying method. If the temperature of the oil is right, the coating should turn lightly golden and crisp in less than three minutes by which time the fish should be cooked through.
If the batter thins out before all the fish have been fried (it will as the ice cubes melt), add more starch and flour, tablespoonful by tablespoonful, and keeping the 1:2 proportion.
As each piece of fish cooks, pick up with kitchen tongs and transfer to a strainer or a plate lines with kitchen paper.
To serve, place the fish fillets on a plate, drizzle some sauce over them, sprinkle with grated lemon or lime and orange zests. Serve the rest of the sauce on the side.