For the fish
50g plain flour
50g cornflour
1 tsp baking powder
turmeric
75ml lager beer
75ml sparkling water
about 1 litre sunflower oil, for frying
400g fillet sustainable cod, hake or haddock, halved
For the chips
750g potatoes, Maris Piper or Desiree, peeled and sliced into thick chips
2 tbsp plain flour
2 tbsp sunflower oil