• Begin by boiling the potatoes. Wash the potatoes and cook them in salted water with the skin on for approx. 20 minutes, depending on their size. Then drain, leave to cool slightly, peel and cut into slices.

Prepare the mustard sauce:

• Peel the onions, finely dice one of them and cut the other into rings. Heat 1 tbsp of oil and the butter in a pan and sauté the diced onions until translucent. Dust with 1 tbsp flour, stir in the mustard, cream and milk and bring to the boil. Season with salt, pepper and sugar and simmer until the desired consistency is achieved.
• Heat 2 tablespoons of oil in a large pan and fry the potato slices, turning carefully, until crispy and brown on all sides. Season generously with salt and pepper. Finally, fry the onion rings. Frying takes at least 15 minutes.

Prepare the fish :

• Rinse the fish fillets and carefully pat dry with kitchen paper. Then cut into larger pieces, season with salt and pepper and dredge in flour.
• Towards the end of the potato frying process, heat the remaining oil in a second pan for the panko fish and fry the fish in it for approx. 3-4 minutes per side until golden brown.
• Arrange the fish on the fried potatoes and serve with the mustard sauce. Serve with salt, pepper and lemon wedges.