1.Heat oil in large heavy based saucepan on high, until a cube of bread sizzles as soon as it is added.
2.Meanwhile, sift flour and spices together into a large bowl. Season to taste. Whisk in beer to form a thick batter (there will be some lumps).
3.Working in hatches, coat cauliflower and onion in batter, allow excess to drain off, then carefully lower into oil for 3-4 minutes, until golden. Remove with a slotted spoon, drain on paper towel. Continue with remainder.
4.Deep-fry mint and parsley or coriander leaves for 30 seconds, until crisp. Remove with a slotted spoon and use as a garnish.
5.Meanwhile to make herb raita, combine in a small bowl, yoghurt, coriander, mint, buttermilk and cumin. Season to taste. Chill. Serve with vegetables.