Reserve 1/4 cup rice flour for dredging and set aside.

In a bowl, whisk together the remaining rice flour, all-purpose flour, baking powder and salt.

Pour in the cold beer and mix gently until combined; do not overmix — a few lumps are fine.

Heat oil in a fryer or deep pot to 350°F (175°C). Pat fish fillets dry, dredge in the reserved rice flour, then dip into the batter to coat.

Fry the battered fillets at 350°F until golden brown and floating, about 3–5 minutes depending on thickness. Drain on a wire rack or paper towels.

Serve immediately with tartar sauce and lemon wedges.