Rinse the fish under cold water.
Season the filets with salt and pepper and roll them up.
Mix flour, bread crumbs, salt and pepper on a large plate.
Dip the filets in the flour mixture and make sure the filets are completely covered.
Fry the filets in butter and oil until they are golden brown.
Cut the onion in thin slices and grate the carrots.
To Make the Brine
Mix all the ingredients for the brine, stir until the sugar has disolved. Mix in the carrots and the onions.
Place the fried fish in a bowl. Pour enough brine over the fish filets until it covers them. Let it sit in the fridge for at least two days before serving. The longer it sits in the fridge, the better it gets!
Serve the fish with new potatoes, rye bread and strong cheddar cheese. That’s as Swedish as it gets!