Steam the potatoes for 15 minutes and set aside.
Season the sole fillets and place it in a preheated oven at 200°C for 10 minutes.
Remove the fillets from the oven and place on hot plates.
Put the juice in a saucepan and cook on a high heat and reduce by half. Grind the salt if necessary and add the chopped parsley.
Serve the fish with boiled potatoes and the sauce.