Peel the potatoes if desired (leaving skin on is fine). Cut into 1/2 to 3/4-inch thick chips/sticks. Rinse under cold water until water runs clear to remove excess starch.

Soak the cut chips in a bowl of cold water for 30 minutes to 1 hour (or at least 20 minutes) to draw out starch for crispiness. Drain and pat completely dry with clean kitchen towels or paper towels.

Heat oil in a deep pot or heavy-bottomed pan to 320°F (160°C). If you don't have a thermometer, heat until a small piece of potato sizzles gently but not vigorously.

Blanch-fry the chips in batches for 4–6 minutes until softened but not browned. Remove with a slotted spoon and drain on a wire rack or paper towels. Let rest while you prepare batter and fish (or chill briefly to speed up).

Increase oil temperature to 375°F (190°C). Return chips to hot oil in batches and fry for 2–4 minutes until golden-brown and crisp. Drain on a rack, immediately season with salt and pepper.

Tartare Sauce

In a small bowl combine mayonnaise, diced dill pickle, chopped capers, chopped parsley, lemon juice, Dijon mustard, salt and pepper. Stir until evenly combined.

Taste and adjust seasoning — add more lemon juice for brightness, salt for seasoning, or a little extra chopped pickle for tang. Chill in the refrigerator while frying for flavors to marry.

Battered Fish

Pat fish fillets dry and cut into serving-size portions (about 4–6 oz each). Season lightly with 1/4 tsp salt and a pinch of pepper.

Set up a dredging station: one shallow dish with 1/2 cup flour for dredging, and a second bowl for the batter.

Make the batter: in the batter bowl whisk together 3/4 cup flour, 1/4 cup cornstarch, baking powder, 1 tsp salt and 1/2 tsp pepper. Whisk in the beaten egg. Slowly pour in the cold beer or sparkling water while whisking until a smooth, slightly thick batter forms. The batter should coat the back of a spoon; if too thick, add 1–2 tbsp more beer/sparkling water. Keep batter cold (place bowl over ice if available).

Heat the frying oil in a deep pot or fryer to 350–375°F (175–190°C). Use a thermometer for accuracy; oil should be hot enough that batter sizzles and cooks quickly without absorbing excess oil.

Dust each fish piece lightly in the 1/2 cup flour, shaking off excess. Hold the fish by one end and dip into the batter, letting excess drip off briefly.

Carefully lower the battered fish into the hot oil, frying in batches to avoid overcrowding (2–3 pieces depending on pot size). Fry for 4–6 minutes, turning if necessary, until the batter is golden-brown and the fish registers 145°F (63°C) or flakes easily when tested with a fork.

Remove fish with a slotted spoon and drain on a wire rack set over a baking sheet. Keep warm in a low oven (200°F / 90°C) while finishing remaining batches.

Serve immediately with hand-cut chips, a generous spoon of tartare sauce, and lemon wedges for squeezing. Enjoy while hot and crispy.