Wash the potatoes and cook covered in salted water for about 20 minutes
Wash the fish, pat dry, sprinkle with lemon juice and salt. Finely dice the onion. Wash celery and apple and cut into pieces
Heat the oil in a frying pan. Sauté the onion, celery and apple. Add bay leaf. Deglaze with stock, bring to the boil. Put the fish into the stock and let it simmer covered for about 10 minutes
Take out the fish. Remove the laurel. Stir in cream and mustard. Thicken sauce and season to taste. Drain the potatoes and arrange everything
The fish chop stays in shape during cooking if you stick the belly flaps together with a wooden skewer