Soaking and Desalting

Much of the Korean pantry is preserved by salt or by drying, and much of it has to be brought back before it can be cooked. Soaking does two jobs. It pulls excess salt out of salted fish and vegetables, and it returns water to dried foods. Sometimes it does a third: drawing out bitterness or compounds that are better removed. None of this is glamorous, but it decides whether the finished banchan tastes balanced or harsh.

Why salted foods need soaking

Salt preserves by pulling water out. The Encyclopedia of Korean Culture explains in its entry on jaban, salted fish, that salt sprinkled on fish draws moisture out of the flesh by osmosis and slows the growth of microbes. It gives rough proportions: about 10 percent salt by weight makes jaban, while 15 to 35 percent takes fish into the territory of jeotgal. Mackerel, croaker, herring, Spanish mackerel and many other fish were treated this way; see godeungeo and jogi.

Fish preserved like this is too salty to eat as it is. The encyclopedia says jaban should be desalted until its salt content falls to about 3 percent or less before it is cooked, for example steamed or gently simmered in an earthenware pot with green onion, garlic, chili flakes and a little water.

Soak in weak brine, not plain water

The same entry makes a point that surprises many cooks: the best liquid for desalting is not fresh water but light brine. Soaking salted fish in about 1.5 percent salt water, it explains, lets the sodium chloride come out first, followed by magnesium and calcium chlorides, which carry the bitter, astringent notes of coarse salt. Plain water pulls out salt too, but it also washes away the fish's savory flavor compounds. In practice this means soaking in a bowl of lightly salted water, tasting a flake now and then, and changing the brine if needed. Keep perishable fish cold while it soaks; the FDA's advice to refrigerate seafood at 40°F (4°C) or below applies here too. See cheonilyeom.

Partial desalting in pickles and jeotgal

Desalting is not always the last step. Among Joseon-era jeotgal, the encyclopedia describes jahajeot, in which abalone, conch, cucumber and radish were first salted, then partly desalted before being packed with tiny shrimp. Salted vegetables follow the same logic at the table. Jjanji, radish packed in heavy salt for winter, was taken out in late spring, sliced thin and floated in vinegared water with green onion and chili, a cold soup that dilutes the salt. The same thinking applies to oiji and to the salted miyeok stems used in miyeok-julgi-bokkeum, which are rinsed and soaked before cooking.

Bracken: soaking out bitterness

Gosari shows soaking at its most purposeful. The encyclopedia explains that young bracken contains an enzyme that breaks down vitamin B1 and must be destroyed before eating. Traditionally the shoots were mixed with wood ash and scalded, or boiled and then left in ash water to cool, which also drew out bitterness; today salt and baking soda replace the ash. Dried bracken is soaked in water and then boiled again before it becomes gosari-namul or goes into soups. Korea's Ministry of Food and Drug Safety adds that bracken contains ptaquiloside, which can cause stomach pain and vomiting, and advises boiling it for at least five minutes and then soaking it in water before use.

For dried radish greens and other dried vegetables, see drying and rehydrating vegetables and siraegi-namul.

Dried seafood

Fresh fish and shellfish are 70 to 80 percent water, the encyclopedia notes, so drying them lets them keep. It sorts dried seafood by method: simply dried (squid, cod), boiled and then dried (anchovies, abalone, sea cucumber, shrimp, mussels), dried by repeated freezing and thawing (pollack), and salted and then dried (croaker made into gulbi). The method tells you how to bring it back. Salted-and-dried fish needs desalting as well as rehydration, while boiled-dried anchovies usually go straight into the pot for broth. Dried pollack for bugeo-guk or bugeo-muchim is moistened just until it softens.

Beans

Dried beans are soaked before cooking for texture and for safety. MFDS warns that beans contain lectins that can cause vomiting and diarrhea if eaten undercooked, and recommends soaking them for at least five hours and then cooking them through. See kongjaban, daedu and black soybeans.

Soaking reduces salt but does not remove it, so salted foods remain a significant source of sodium; see sodium in Korean food.