Prawn and Sweet Onion Tempura

Tempura sounds straightforward, but getting the batter right can be tricky. After many so-so results, I have finally come up with a failproof recipe. A mix of regular and fine flours, such as cornflour, blended with ice-cold soda water creates a blistering coating. The batter should never be thick – it only needs to lightly coat the vegetables or prawns, which should be sizzled to a pale colour, not browned.