Drizzle the fish fillets with 1-2 tablespoons of lemon juice and season with salt. Heat 50 g butter with the oil and fry the fillets until golden brown on both sides, remove and keep warm.
Deglaze the roast set with the remaining lemon juice and the wine, let it boil down for 5 minutes, then stir in the remaining butter in flakes and season with salt and pepper. Arrange the fish fillets on plates and pour the sauce over them.