In a wide, shallow bowl or rimmed baking sheet, whisk together the all-purpose flour, cornstarch, cornmeal (if using), paprika, garlic powder, onion powder, dried oregano, cayenne, 1.5 tsp salt, and 1 tsp black pepper until evenly combined.

Prepare wet mix

In a separate bowl, beat the 2 eggs lightly, then whisk in the buttermilk, cold sparkling water or beer, and 1 tsp hot sauce (if using). This should be a pourable batter with some thickness; adjust with a splash more liquid if too thick.

Season seafood

Pat the mahi mahi, shrimp, and your chosen protein dry with paper towels. Sprinkle each piece lightly with the 1 tsp kosher salt and 1/2 tsp black pepper, rubbing gently so the seasoning adheres.

Breading & Batter

Two-step breading (recommended for best crunch)

Set up a breading station: seasoned dry mix in one shallow pan and the wet batter in another. Working in batches, dredge each piece of seafood or protein first in the dry mix, shaking off excess, then dip into the wet batter so it is evenly coated, and finally return it to the dry mix for a second light coating. For shrimp, you may skip the second dry coating if you prefer a lighter crust.

Rest briefly

Place breaded pieces on a wire rack and let rest 5–10 minutes. This helps the coating adhere and prevents it from falling off in the oil.

Frying

Heat oil

Pour enough neutral oil into a heavy skillet or Dutch oven to reach about 1.5 inches deep (roughly 1–1.5 cups). Heat the oil over medium-high until it reaches 350–360°F (175–182°C). If you do not have a thermometer, test by dropping a small pinch of batter — it should sizzle and rise steadily without burning immediately.

Fry in batches

Carefully lower breaded pieces into the hot oil without overcrowding. Fry mahi mahi pieces for 3–4 minutes per side (6–8 minutes total) until golden brown and cooked through (internal temp 145°F / 63°C). Fry shrimp for 2–3 minutes until golden and opaque. Fry your choice protein according to type: chicken strips 4–5 minutes per side (thin strips) until cooked through; calamari rings 1.5–2 minutes total until just golden (do not overcook). Adjust times for piece size. Maintain oil temperature between 330–360°F by reducing or raising heat as needed.

Drain

Use a slotted spoon or spider to transfer fried pieces to a wire rack set over a baking sheet or to paper towels to drain excess oil. Immediately sprinkle lightly with a pinch of salt. Keep finished pieces in a warm oven (200°F / 95°C) on the rack while frying remaining batches to keep them crisp.

Sauce & Finish

Make tartar sauce (optional)

While frying or before serving, combine mayonnaise, dill pickle relish, lemon juice, chopped capers (if using), 1/4 tsp salt, and 1/8 tsp black pepper in a small bowl. Taste and adjust acidity or seasoning as desired.

Plate and garnish

Arrange fried mahi mahi, shrimp, and chosen protein on a serving platter. Garnish with chopped fresh parsley and lemon wedges. Serve immediately with tartar sauce and any other accompaniments (coleslaw, fries, rice, or salad).