For the plaice fillets with pumpkin seed crust, squeeze the lemon. Acidify the fish fillets with the lemon juice and salt them. Cover the skin side with the chopped pumpkin seeds and press only lightly.
Heat a mixture of oil and butter in a pan and fry the plaice fillets first on the skin side, turn and finish frying briefly. Lift out, drain on kitchen paper and arrange garnished with lemon balm leaves.