Rinse the shrimp under cold water, pat dry thoroughly with paper towels. If not already done, peel and devein the shrimp; leave tails on for presentation if desired.

Marinate

Place the dried shrimp in a bowl and pour the buttermilk over them. Toss to coat and let sit for 15–20 minutes in the refrigerator. This tenderizes and flavors the shrimp.

Make batter

In a medium bowl, whisk together the flour, cornstarch, baking powder, 1 tsp salt, 1/2 tsp black pepper, paprika, garlic powder and cayenne (if using). Add the cold sparkling water or beer and stir until just combined; the batter should be slightly thick but still pourable. Keep the bowl over a larger bowl of ice or refrigerate briefly so the batter stays cold (cold batter gives a crisper fry).

Heat oil

Pour about 3 inches of vegetable oil into a deep pot or Dutch oven. Heat to 350°F (175°C). If you don't have a thermometer, test with a small pinch of batter—if it sizzles and browns in about 30–45 seconds, the oil is ready.

Coat and fry shrimp

Working in small batches (4–6 shrimp at a time to avoid crowding), remove shrimp from the buttermilk allowing excess to drip off, then dip each into the batter to coat completely. Carefully lower battered shrimp into the hot oil. Fry until golden brown and cooked through, 2–3 minutes depending on shrimp size. Use a slotted spoon to transfer fried shrimp to a wire rack set over a baking sheet or paper towels; keep warm in a 200°F (95°C) oven if desired while you finish remaining batches.

Fries (Chips)

Prepare potatoes

Peel the potatoes if desired and cut into 1/3–1/2 inch thick sticks for classic chips. Place cut fries in a large bowl of cold water and let soak at least 20 minutes (or up to 2 hours) to remove excess starch—this helps them become crisp.

Par-fry (optional but recommended)

Drain and pat the potato sticks completely dry with kitchen towels. Heat oil in a heavy pot to 325°F (160°C). Fry the potatoes in batches for 3–4 minutes until they are softened and just beginning to color. Remove with a slotted spoon and drain on a wire rack or paper towels.

Final fry

Increase oil temperature to 375°F (190°C). Fry the par-fried chips in batches for 2–3 minutes more until golden and crisp. Remove and drain, then immediately season with 1 tsp salt and 1/2 tsp black pepper (adjust to taste).

Sauce & Finish

Serve

Arrange the golden fried shrimp and hot chips on a platter or individual plates. Sprinkle chopped parsley over the fries if using, add lemon wedges and a small bowl of tartar sauce for dipping. Serve immediately while everything is hot and crispy.

Notes

If you prefer a lighter coating, instead of batter you can dredge shrimp in seasoned flour (same flour mixture without adding water) and fry until golden. Maintain oil temperature between batches for consistent results. Total make-ahead: potatoes can be cut and soaked earlier; shrimp can be kept briefly in buttermilk in the fridge until ready to batter.