Lutefisk is sun dried fish that when ready to cook has lye added to it, then the lye is removed, a sauce is added to provide flavor.
"As I understand it lute fish is a (rather late, I think) invention in the long series of food preservation techniques you find in winter climates. You had to come up with methods to preserve the food from when you could get it. Salting, drying as pemmican or lute fish, preserving in vinegar, fermentation of fish, and possibly other techniques that people stumbled on.
(Self-fermentation of fish is the most interesting IMO, since the enzymes that do the process is from the fish itself, IIRC the bones in the head. Someone must have accidentally fermented instead of salt preserved a can of fish, and found out that it was still edible and even enjoyably spicy. Despite the somewhat... unique... smell.)"
from Torbjorn at here:
Pharyngula: If you are what you eat…
also canning/bottling after boiling
