Prepare the Fish:
Rinse the fish fillets and pat them dry with paper towels. Place the fish fillets in a large bowl and cover with buttermilk. Let them soak for at least 30 minutes in the refrigerator.
Prepare the Coating:
In a large mixing bowl, whisk together the cornmeal, flour, Old Bay seasoning, garlic powder, onion powder, paprika, salt, and pepper.
Heat the Oil:
In a deep fryer or large skillet, heat about 2 inches of vegetable oil to 350°F (175°C).
Coat the Fish:
Remove the fish fillets from the buttermilk, letting any excess drip off. Dredge the fish in the cornmeal mixture, pressing gently to ensure it adheres well. Place the coated fillets on a baking sheet.
Fry the Fish:
Carefully place the coated fish fillets in the hot oil, a few at a time, and fry until golden brown and crispy, about 3-4 minutes per side. Use tongs to turn the fillets and ensure even cooking. Transfer the fried fish to a wire rack set over a baking sheet to drain any excess oil.
Prepare the Tartar Sauce:
In a small bowl, whisk together the mayonnaise, sweet pickle relish, lemon juice, Dijon mustard, chopped dill, salt, and pepper until well combined. Adjust the seasoning to taste.
Serve:
Serve the fried fish hot with a side of tartar sauce and lemon wedges. Enjoy your delicious and crispy Southern-style fried fish!