Cook potatoes in their skins in salted water for 20 minutes on the stove and let cool. (ev. Cook on the stove the day before) Drizzle fish fillets with lemon juice, leave to infuse for 10 min., season with salt and season with pepper. Coarsely grate potatoes and Gouda, chop parsley and mix everything together. Place half of the fish fillets on the bottom of a greased gratin dish, cover with a third of the potato and cheese mixture, then add the remaining fillets and the rest of the potato mixture. Bake in a heated oven at 225 degrees (200 degrees with convection oven) for 20 minutes. A green leaf salad goes well with it! The cod can be replaced by pollack or redfish.
Tip: Lemons give dishes a fresh touch. Choose deliberately ripe, rich yellow lemons!