Batter provides a protective coating, which keeps fish succulent and moist. A high cooking temperature (180-190°C) is necessary for the best result, and the oil should be carefully chosen, both for its ability to reach the required temperature and how it affects the flavour of the fish;
To test the temperature of the oil, drop in a cube of white bread, it should brown all over in about 30 seconds. Remove the bread and discard.
Lower the batter-coated fish into the hot oil. Cook large pieces of fish one at a time for 7-10 minutes to ensure even cooking.
When golden and crisp, lift the basket out of the fryer. Shake the basket to remove excess oil, then drain the fish on to paper towels. Season before serving.