Tartare sauce: combine all the ingredients for tartare sauce together in a bowl and set aside.
Pat your pieces of fish dry. Sprinkle over a bit of salt and coat the fish in some cornflour. Brush off any excess flour from the fish and set aside.
Heat up a pot of oil to 180-190C / 350-375F. Fry the chips until golden brown, remove from oil and sprinkle over some salt. Or you can just airfry frozen chips if you want a shortcut.
Batter: Combine the flour, baking powder and a pinch of salt into a bowl. Pour in the cold beer and whisk until well combined.
Dip the fish into the batter to get an even coat and carefully drop it into the hot oil (be careful of your fingers!). Fry for ~5-6 minutes or until golden and cooked through.
Serve with chips and tartare sauce.