Season with salt and black pepper; stir until evenly combined. Taste and adjust lemon, salt or mustard to preference. Cover and refrigerate while preparing the fish and fries to allow flavors to meld (at least 15 minutes).

Chunky Fries

Wash and scrub the potatoes. Leave the skins on for texture. Cut each potato into chunky fries: halve lengthwise, then cut each half into 3–4 thick sticks so you end up with roughly 3/4–1 inch thick pieces.

Place cut fries in a large bowl of cold water and soak for 20–30 minutes to remove surface starch. Drain and pat completely dry with clean kitchen towels or paper towels.

Heat oil in a deep heavy-bottomed pot or deep fryer to 325°F (160°C). If you don't have a thermometer, heat until a cube of bread browns slowly in about 60 seconds.

Working in batches, fry the dried potatoes at 325°F (160°C) for 4–6 minutes until they are soft and pale (not browned). Remove with a slotted spoon and drain on a wire rack or paper towels. Let cool 5 minutes.

Increase oil temperature to 375°F (190°C). Fry the par-cooked fries in batches again for 2–3 minutes until golden and crisp. Remove and drain on paper towels, immediately season with kosher salt, pepper and toss with chopped parsley if using.

Crispy Breaded Sea Bass

Pat the sea bass fillets dry with paper towels. Season both sides lightly with 1 tsp of the salt and 1/2 tsp of the black pepper reserved for the fish.

Set up a breading station: one shallow bowl with flour (seasoned with 1/2 tsp salt, 1/4 tsp pepper, garlic powder and paprika), one bowl with beaten eggs mixed with milk, and one shallow plate with the cornmeal or panko.

Dredge each fillet first in the seasoned flour, shaking off excess, then dip into the egg mixture, allowing excess to drip off, and finally press into the cornmeal/panko to coat evenly. Place coated fillets on a rack while you heat the oil.

Pour about 1 to 1 1/2 cups vegetable oil into a large skillet (enough to shallow-fry and come halfway up the fillets) and heat to medium-high (about 350°F/175°C). The oil should shimmer but not smoke. Test with a small breadcrumb — it should sizzle steadily.

Working in batches (do not crowd), carefully place fillets in the hot oil. Fry for 3–4 minutes per side, until crust is golden brown and internal temperature reaches 130–135°F (54–57°C) and flakes easily. Thinner fillets may take less time; thicker fillets may need an extra minute.

Transfer cooked fillets to a paper-towel-lined plate or wire rack to drain. Keep warm in a low oven (200°F/95°C) if needed while finishing remaining fillets.

Serve each fillet with a lemon wedge, a generous scoop of chunky fries and a dollop of tartare sauce.