Igalaaq (cod in sauce)

Instructions

1. Cook the peeled potatoes in boiling salted water for 20 minutes, then drain them.
2. Meanwhile, melt the butter in a saucepan and sweat the sliced onion for 4 minutes without browning.
3. Sprinkle in the flour and stir for 1 minute to make a blond roux.
4. Pour in the milk gradually while whisking to get a smooth sauce, then add the bay leaves, salt, pepper and nutmeg.
5. Lay the cod fillets in the sauce, cover and simmer gently for 10 minutes until the fish breaks apart.
6. Remove the bay leaves, then off the heat stir in the mustard and, if using, the egg yolk. Serve the cod coated in sauce with the potatoes and parsley.