Haddock Cooked in Doogh Batter

This is my stab at a sort of ‘halal alternative to beer’ batter. They love beer (ab joh – literally, barley water) in Iran – but of course it is all non-alcoholic and often rather sweet. Made with doogh, the fizzy salted yoghurt drink beloved by Iranians in hot weather, this batter achieves wonderful sharp overtones. You can use any fish, but I find that the slightly more robust flavour of haddock does the job very nicely.