Clean and gut the fish, if not already prepared.
Mix salt and sugar in a bowl and rub the mixture all over the fish.
Optionally, add spices to the salt and sugar mixture for extra flavor.
Place the fish in a clean container, cover, and let it cure in the refrigerator for 3-4 days.
After curing, transfer the fish to a large, airtight container.
Press the fish down and cover with a lid or plastic wrap.
Leave the fish to ferment in a cool, dark place for 2-3 months.
Remove the fish from the container and rinse off any excess salt.
Slice the rakfisk thinly and serve with boiled potatoes, sour cream, flatbread or rye bread.
Optionally, garnish with chopped red onions and fresh dill.
Enjoy your meal!