For the fiskbullar, puree the well boned fish in a food processor or finely mince twice. Moisten white bread crumbs with milk or whipping cream. Mix fish mixture with eggs and butter, add white bread and season with salt, pepper and a pinch of nutmeg. If desired, mix in chopped herbs and season with lemon juice.
If the mixture is too soft, firm it up with a little flour or breadcrumbs. Form small dumplings with two tablespoons, roll in breadcrumbs and fry in hot butter or oil until crispy.
Meanwhile, cut the onion into rings or strips and fry in plenty of butter until golden brown. Gently lift out the finished fiskbullar, arrange and garnish with the onion rings. If desired, drizzle remaining butter over the top. Serve the fiskbullar (Norwegian fish dumplings) with parsley or dill potatoes and warm fish-upper sauce (or dill sauce).