Crispy Buttermilk-Fried Catfish

Preparation

1. Step 1

   Whisk 2 cups buttermilk, 1½ tsp. smoked paprika, ¼ tsp. cayenne pepper, 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, and 1 tsp. garlic powder in a shallow bowl; season with freshly ground black pepper. Add four 4–6-oz. catfish fillets, patted dry, to marinade and turn to coat. Let sit at room temperature, turning occasionally, 10–15 minutes.

   Step 2

   Meanwhile, stir ¾ cup finely chopped pickles, ½ cup mayonnaise, 2 Tbsp. whole grain mustard, 1 Tbsp. finely chopped chives, 1 Tbsp. fresh lemon juice, ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt, and remaining 1 tsp. garlic powder in a small bowl to combine; season with black pepper. Set rémoulade aside.

   Step 3

   Whisk ½ cup medium-grind cornmeal, ⅓ cup all-purpose flour, and 1½ tsp. Diamond Crystal or 1 tsp. Morton kosher salt in another shallow bowl.

   Step 4

   Working with 1 fillet at a time, lift fish from marinade, letting excess drip back into bowl. Dredge in cornmeal mixture, pressing firmly to adhere. Transfer fish to a baking sheet.

   Step 5

   Pour 3–4 cups vegetable oil into a large cast-iron skillet to come ½" up sides; fit with thermometer. Heat over medium-high until thermometer registers 350°.

   Step 6

   Working in 2 batches and returning oil to 350° between batches, fry fish until golden brown, about 2 minutes per side. Transfer to a wire rack set inside a clean rimmed baking sheet and immediately season with salt.

   Step 7

   Serve fish with ketchup and reserved rémoulade.

   Do Ahead: Rémoulade can be made 1 day ahead. Cover and chill.