Why a specific brand of kosher salt? As explained in great detail in her excellent book CookWise, food scientist Shirley Corriher tells us that Diamond Crystal salt crystals are actually pyramids-as opposed to grains-which are much more likely to adhere to food. In fact, these hollow pyramids, or crystals, also dissolve twice as fast as granular salts, including Morton kosher salt.
Fine cooks often cite another reason for preferring Diamond Crystal kosher salt: measure for measure, because the “grains” are bigger, thereby taking up more room in the measuring spoon, Diamond Crystal kosher salt has about half the sodium of table salt or fine sea salt. As the accompanying chart illustrates, it takes 2 teaspoons of Diamond Crystal kosher salt to contribute the amount of sodium found in 1 teaspoon of common table salt. When you’re seasoning to taste, you have more play with the kosher salt than table salt because the grains are bigger. It’s harder to overseason with salt that tastes half as salty, measure for measure. Another reason fine cooks eschew table salt is that it’s treated with calcium silicate to make it flow freely. To many, including me, this gives salt a metallic aftertaste.