Dry & cut fish: Pat fish dry using paper towels or a tea towel. Cut into 4 fillets. If you have very thick fillets, cut in half horizontally

Dusting bowl: Place ¼ cup rice flour in a shallow bowl.

Heat oil: Heat 6cm / 2" – 3" oil in a large heavy based pot over medium high heat to 190°C/375°F.

Salt & dust: While oil is heating, sprinkle 3 or 4 pieces of fish with a pinch of salt, then coat in rice flour and shake off excess. You can leave them like this for up to 10 minutes.

Cold batter: Just before cooking, whisk together the flour, rice flour, baking powder and salt. Add very cold beer into the batter and whisk just until incorporated evenly into the flour. Do not over-mix, do not worry about flour lumps . It should be a fairly thin batter but fully coat the back of a spoon. If too thick, add beer 1 tsp at a time.

Dunk a piece of fish in the batter, the let the excess drip off very briefly.

Carefully lower into oil, dropping it in away from you, one piece at a time. Don't crowd the pot; fry in batches. Fry for 3 minutes, flipping after about 3 minutes, until deep golden.

Drain: Drain on paper towels. Repeat with remaining fish.

Split Brioche buns in half and toast in a pan with some butter until golden brown.

Start assembling the sandwich by putting tartar sauce on the bottom bun with some pickles. Place the crispy fish with cheese on top of the bun, shred some lettuce on top and place the other bun with more tartar sauce on top.