The one time it's OK to be salty
Chefs and cookbook authors can get really finicky about their salt preferences, often specifying which type of salt is best to use in any given recipe. But, for the home cook with limited space in the pantry, it’s easy to write off the different types of salt—because what’s the difference between sea salt and kosher salt, anyway? Well, it turns out that even though sea salt and kosher salt and even table salt are all chemically the same, where texture is concerned, there is a big difference between kosher salt and sea salt and table salt. So let’s start by looking at the difference between table salt and sea salt.
Table salt is the really fine stuff that you find in diner salt shakers. According to the Mayo Clinic, the main difference between that fine, table salt and sea salt is the way in which the salt is processed. “Table salt is typically mined from underground salt deposits,” writes Katherine Zeratsky, R.D., L.D. “Table salt is more heavily processed to eliminate minerals and usually contains an additive to prevent clumping.”
To make sea salt, a salt maker takes seawater and lets it evaporate in a series of low-lying ponds or marshes so all that’s left is the sea salt. As a result of this production, and the lack of further intensive processing, sea salt is generally flakier and coarser in texture than traditional table salt. Just think Maldon salt, which almost looks like flakes of dandruff in the most appealing way possible.
Kosher salt can be produced by either of these methods—that is by mining solid, underground salt deposits or by evaporating seawater. That’s because what matters most with kosher salt is the texture, not the production method or even the fact that it’s kosher. The name is actually kind of misleading, since kosher salt isn’t always kosher according to Jewish law. As Rochel Chein explains on Chabad.org, “A better term would be ‘koshering salt.’”
In Jewish kosher tradition, all blood must be removed from the meat after slaughter to make it ready for consumption. “This is normally accomplished by salting the meat, as salt draws out blood,” writes Chein. “Table salt is too thin and will dissolve into the meat without drawing out the blood, and salt that is too coarse will roll off. The salt that is ‘just right’ for koshering meat is called ‘kosher salt.’”
This difference in texture is why you cannot really substitute table salt in a recipe that calls for kosher salt, especially when you’re measuring by volume. J. Kenji López-Alt explains for Serious Eats, “A cup of table salt will have twice the salting power of a cup of Diamond Crystal kosher salt.” The coarse texture is why kosher salt is better for distributing seasoning evenly than table salt.
You could use sea salt instead of kosher salt, but sea salt is generally more expensive than coarse kosher salt, so it's best for finishing or smaller portions rather than seasoning large cuts of meat. Really, if you want to cover your salt bases, you don't need sea salt at all—especially if you have both kosher salt and table salt in your pantry. But, if you're really in a pinch and need to substitute table salt for kosher salt, López-Alt recommends using half the amount of table salt as you would kosher salt. (In other words, if a recipe calls for a tablespoon of kosher salt, use only half a tablespoon of table salt.) Because, at the end of the day, it's all chemically the same salt, and it'll all make your food taste better.