For those who are uneducated to Lutefisk here is a good definition.

Lutefisk is made from salted/dried whitefish (normally cod, but ling is also used), prepared with lye, in a sequence of particular treatments. The watering steps of these treatments differ slightly for salted/dried whitefish because of its high salt content. The first treatment is to soak the stockfish in cold water for five to six days (with the water changed daily). The saturated stockfish is then soaked in an unchanged solution of cold water and lye for an additional two days. The fish will swell during this soaking, attaining an even larger size than in its original (undried) state, while its protein content decreases by more than 50 percent, producing its famous jelly-like consistency. When this treatment is finished, the fish (saturated with lye) has a pH value of 11–12, and is therefore caustic. To make the fish edible, a final treatment of yet another four to six days of soaking in cold water (also changed daily) is needed. Eventually, the lutefisk is ready to be cooked.

In Finland, the traditional reagent used is birch ash. It contains high amounts of potassium carbonate and hydrocarbonate, giving the fish a more mellow treatment than would sodium hydroxide (lyestone). It is important to not incubate the fish too long in the lye, because saponification of the fish fats may occur, effectively rendering the fish fats into soap. The term for such spoiled fish in Finnish is saippuakala (soap fish).

Cooking pots at a church supper: with this method, the lutefisk was boiled for about five minutes, until translucent, then promptly served.After the preparation, the lutefisk is saturated with water and must therefore be cooked carefully so that it does not fall into pieces.

Lutefisk does not need any additional water for the cooking; it is sufficient to place it in a pan, salt it, seal the lid tightly, and let it steam cook under a very low heat for 20–25 minutes. It is also possible to do this in an oven. There, the fish is put in an ovenproof dish, covered with aluminium foil, and baked at 225 °C (435 °F) for 40–50 minutes.

Another option is to parboil lutefisk. Wrap the lutefisk in cheesecloth and gently boil until tender. This usually takes a very short time, so care must be taken to watch the fish and remove it before it is ready to fall apart. Prepare a white sauce to serve over the lutefisk.

Lutefisk sold in North America may also be cooked in a microwave oven. The average cooking time is 8-10 minutes per whole fish (a package of two fish sides) at high power in a covered glass cooking dish, preferably made of heat resistant glass. The cooking time will vary, depending upon the power of the microwave oven.