Pat the plaice fillets dry on both sides with paper towels. Season both sides lightly with sea salt and black pepper. If using lemon, cut half the lemon into wedges for serving and zest the other half for the coating.

Coating & frying

Ready the coating

On a shallow plate combine the all-purpose flour and lemon zest. Spread chopped parsley on a separate small plate for finishing (or sprinkle into the flour if you prefer a herby crust).

Warm the pan

Place a large nonstick or stainless-steel skillet over medium heat. Add the butter and olive oil and let the butter melt and foam but not brown (about 1–2 minutes). The oil raises the smoke point and helps even browning.

Dredge the fish

Lightly dredge each seasoned plaice fillet in the flour-zest mixture, shaking off excess. The thin skin-on fillets need only a light coating to deliver a crisp exterior while remaining delicate inside.

Fry the plaice

Carefully place the fillets skin-side down into the hot butter-oil mixture. Do not overcrowd the pan; fry in batches if necessary. Cook undisturbed for 2½–3 minutes until the skin side is golden and crisp. Using a thin spatula, gently flip the fillets and cook the flesh side for another 1½–2 minutes until opaque and just cooked through (internal temperature ~60–63°C / 140–145°F). Total cook time will depend on thickness but typically 4–5 minutes per fillet.

Finish & garnish

Transfer the cooked plaice to a warm plate. Squeeze the reserved lemon wedges over the fillets and sprinkle with chopped parsley. If desired, spoon any browned butter from the pan over the fish for extra flavor.

Optional quick sauce

Deglaze for sauce

With the pan still over medium heat, pour in the white wine or fish stock to deglaze, scraping gently to release browned bits (be careful of steam). Reduce by about half, 1–2 minutes.

Mount with butter

Lower the heat to low. Whisk in the cold butter cubes a few at a time until the sauce becomes glossy and slightly thickened. Stir in the rinsed capers, taste, and adjust seasoning with a little salt or a squeeze of lemon if desired. Spoon the sauce over the plated plaice.