Cajun Flounder Fish Sandwich (Popeyes Copycat)

Why You’ll Love This Recipe

• All the peppery, coastal crunch of the drive-thru classic, made fresh at home.
• Ultra-crispy cornmeal–flour crust that stays shatteringly crisp.
• Quick buttermilk-hot sauce marinade for juicy, seasoned fish.
• Bright, spicy tartar and dill pickles balance the richness perfectly.

Grocery List

• Produce: Lemon, fresh dill or chives, garlic (optional)
• Dairy: Buttermilk, butter, brioche buns
• Pantry: Flounder fillets, mayonnaise, dill pickle chips, dill relish, capers, Louisiana-style hot sauce, Dijon mustard, flour, fine yellow cornmeal, cornstarch, baking powder, peanut or canola oil, paprika, cayenne, garlic powder, onion powder, dried thyme, dried oregano, kosher salt, black pepper

Full Ingredients

Spicy Tartar Sauce

• 2/3 cup mayonnaise
• 2 tbsp dill pickle relish (drained)
• 1 tbsp capers, chopped (optional but great)
• 2 tsp Louisiana-style hot sauce
• 1 tsp Cajun seasoning (salt-free preferred) or 3/4 tsp paprika + pinch cayenne
• 2 tsp fresh lemon juice
• 1 tsp Dijon mustard
• 1 tbsp finely chopped fresh dill or chives

Homemade Cajun Spice Blend (optional; use 3 tsp in recipe)

• 2 tsp sweet paprika
• 1/2 tsp smoked paprika
• 1 tsp garlic powder
• 1 tsp onion powder
• 3/4 tsp dried oregano
• 3/4 tsp dried thyme
• 1 tsp kosher salt
• 1/2 tsp black pepper
• 1/4–1/2 tsp cayenne pepper

Fish & Marinade

• 4 flounder fillets (4–5 oz each), about 1/3–1/2 inch thick
• 3/4 cup buttermilk
• 2 tbsp Louisiana-style hot sauce
• 1 tsp Dijon mustard
• 1 tsp kosher salt
• 1/2 tsp garlic powder
• 1/2 tsp onion powder
• 1/2 tsp paprika
• 1/4 tsp cayenne pepper

Cajun Dredge

• 1 cup all-purpose flour
• 1/2 cup fine yellow cornmeal
• 1/4 cup cornstarch
• 2 tsp Cajun seasoning (from blend above or store-bought)
• 1 tsp baking powder
• 1/2 tsp kosher salt (reduce to a pinch if your Cajun seasoning is very salty)

For Frying & Assembly

• 1.5 quarts peanut or canola oil (2–3 inches in a Dutch oven)
• 4 brioche buns, split
• 2 tbsp softened butter
• 16 dill pickle chips
• Lemon wedges (optional, for serving)

Step-by-Step Instructions

Step 1: Mix the spicy tartar

In a small bowl combine mayonnaise, dill pickle relish, capers, hot sauce, Cajun seasoning, lemon juice, and Dijon. Fold in dill or chives. Cover and refrigerate so the flavors meld while you prepare the fish.

Step 2: Prep and marinate the flounder

Pat flounder fillets very dry. In a shallow dish, whisk buttermilk, hot sauce, Dijon, salt, garlic powder, onion powder, paprika, and cayenne. Submerge the fillets, cover, and refrigerate 20 minutes. This seasons the fish and helps the coating stick.

Step 3: Mix the Cajun dredge

In a wide bowl, whisk flour, cornmeal, cornstarch, Cajun seasoning, baking powder, and salt. Set a wire rack over a sheet pan for resting breaded fish and draining after frying.

Step 4: Heat the oil and set up the fry station

Pour 2–3 inches of oil into a heavy pot and heat to 350°F (175°C) over medium heat. Use a deep-fry or instant-read thermometer and adjust heat to maintain 325–350°F during frying. Keep tongs and a spider skimmer handy.

Step 5: Dredge the fillets for max craggy crunch

Working one piece at a time, let excess marinade drip off. Press into the dredge, turning and firmly patting so a rough, even coating adheres. For extra cragginess, dip quickly back into the marinade and dredge a second time. Place on the wire rack and rest 5 minutes; this sets the coating.

Step 6: Fry in batches to golden and crisp

Fry 2 fillets at a time until deep golden brown, about 2.5–3.5 minutes per side, or until the thickest part reaches 145°F. Avoid crowding and keep the oil between 325–350°F. Transfer to the rack to drain. Lightly sprinkle a pinch of Cajun seasoning while hot if you like extra kick.

Step 7: Toast the brioche and assemble

Spread cut sides of buns with butter and toast in a skillet over medium heat until golden, 45–90 seconds. To assemble, schmear the bottom bun with spicy tartar, add 4 pickle chips, set a crispy flounder fillet on top, add another spoon of tartar if desired, and cap with the top bun. Serve immediately with lemon wedges.

Pro Tips

• Use fine cornmeal plus cornstarch and a touch of baking powder for a crisper, lighter crust.
• Let breaded fish rest before frying so the coating adheres and won’t blow off in the oil.
• Maintain oil temp: too cool makes soggy breading; too hot scorches spices. Fry in small batches.
• Wet-hand/dry-hand method keeps your dredge from clumping and your coating even.
• Drain relish and capers well so the tartar stays thick and doesn’t waterlog the bun.

Variations

• Air Fryer: Spray breaded fillets generously with oil. Cook at 400°F for 10–12 minutes, flipping halfway; toast buns separately.
• Oven-Baked: Preheat a sheet pan with a wire rack at 450°F. Spray breaded fillets with oil and bake 12–15 minutes until crisp and 145°F.
• Fish Swap: Thin cod, haddock, or catfish fillets work well; adjust cook time based on thickness.

Storage & Make-Ahead

The spicy tartar can be made up to 7 days ahead (refrigerated). For best texture, fry fish just before serving. Leftover fried fillets keep 1–2 days in the fridge; re-crisp on a rack at 400°F for 8–10 minutes. Toast buns fresh. Avoid freezing raw breaded flounder (delicate); if needed, freeze cooked fillets in a single layer and reheat at 400°F until hot and crisp.

Nutrition (per serving)

Approx. 820 calories; 50 g fat; 58 g carbs; 28 g protein; 1,450 mg sodium. Values are estimates and will vary with oil absorption and bun size.