Step 1

In a large bowl, sprinkle chicken with rice flour; season generously with kosher salt and pepper, tossing to coat. Pour oil into a large pot to a depth of 2 inches. Place over medium-high heat until a thermometer registers 350 degrees.

Step 2

Whisk together both flours, 1/2 teaspoon kosher salt, and 1/4 teaspoon pepper. Whisk in 3/4 cup water until a smooth, thin batter forms.

Step 3

Working in batches, dip pieces of chicken into batter, allowing excess to drip off. Transfer to oil and fry until pale golden, 6 minutes. Remove and shake lightly in a colander to drain; transfer to paper towels. Bring oil temperature back to 350 degrees, then return chicken to oil and fry a second time until golden brown and a thermometer inserted into thickest parts (avoiding bones) registers 160 degrees, about 6 minutes for small pieces, about 8 minutes for large. Transfer to a wire rack set in a rimmed baking sheet; season with flaky salt. Serve warm or room temperature.