Make the batter by mixing self-raising flour, cornflour, baking powder, salt and pepper in a bowl and whisking in the spring water until you have a smooth batter.
Step 3 : Fry the chips
Heat the oil in a sturdy wok or deep-fat fryer to 120C. Fry the chips for 5 mins. Remove with a strainer and drain on kitchen paper.
Step 4 : Fry the fish
Turn up the oil to 180C.
Dip the fish in seasoned plain flour. Now dip in the batter, allow to drip off, then, holding the tail end, place in the hot oil. Use the strainer to prevent sinking, so that the batter fries evenly (about 4 mins). Cook until crisp and remove to kitchen paper.
Step 5 : Finish the chips
Return the heat to 180C and place the half-cooked chips back in. Cook for 5 mins until golden and crispy.
Step 6 : To serve
Remove, drain and serve with the fish and tartare sauce.