If you buy frozen fish for this dish, buy blast-frozen fish so that half the weight does not go away when defrosted. For these fish cakes, you can use not only cod, but also its relative - pollock.
Preheat oven to 200°C. Wash potatoes with a brush, wrap individually in foil and bake until tender, about 40 minutes. Plunge the finished potatoes with cold water, cool slightly, peel and grate. Do not turn off the oven. Peel and very finely chop the onion. Melt a couple of tablespoons of butter in a frying pan, put the onion, salt and fry over low heat for about 15 minutes. The onion should turn golden, but not brown.
Pour paprika and curry into the onion, cook, stirring, 20 seconds. Remove from fire and cool. Chop both types of fish with a heavy knife or pass through a meat grinder with a fine grate. Salt and pepper, mix with potatoes.
Remove the tough stems from the dill, finely chop the leaves and add to the minced meat. Add fried onion and mix thoroughly.
Lubricating your hands with oil, make small round plump cutlets from minced meat, roll in breadcrumbs. Fry over high heat until golden brown on both sides, then finish in the oven, about 10 minutes.