Peel and wash the potatoes and cook in boiling salted water for 20-25 minutes.
Wash the salmon and dab dry. Season with salt and pepper and sprinkle with lemon juice. Heat olive oil in a large pan. Fry the fish fillets in it first on the skin side for 4-5 minutes until crispy.
Turn the fish fillets and fry for another 3-4 minutes.
Meanwhile melt the fat in a pot. Stir in flour, sweat briefly. Add milk and broth bit by bit while stirring. Bring to the boil, simmer for about 6 minutes, remove from the heat. Wash parsley, shake dry, pluck leaves and chop finely.
Stir the parsley into the sauce, season to taste with salt, pepper and lemon juice. Drain the potatoes and arrange with 2 salmon fillets, sauce and lemon wedges.