Years ago while on vacation in Maine I tried boiling down a pot of seawater until the salt crystallized on the bottom. It worked in the sense that I successfully boiled off the water, but the salt itself was a total failure—way too bitter and harsh. In addition to sodium chloride, seawater contains a mix of minerals—mainly calcium, magnesium, and sulfate. The calcium and magnesium salts can make sea salt very bitter. There are a couple of tricks that salt producers use to eliminate these compounds and produce clean, briny-tasting sea salt. The calcium salts crystallize before sodium chloride does, so they can be removed before they get incorporated into the salt crystals. And the magnesium salts can actually be washed off the finished salt by using a saturated salt solution (it sounds weird, but trust me, it works). I tried both of these techniques on the seawater that I scooped up from the rocky coast of Marblehead, Massachusetts, and they both made a marked improvement in bitterness. I also ran some tests to figure out the best way to get a coarse, flaky-textured salt—perfect for sprinkling on steak, seared fish, and cultured butter. Generally speaking, slower evaporation leads to larger crystal formation (we tried one batch left uncovered for a couple of days in the kitchen and got some particularly beautiful pyramid-shaped salt crystals). I found that I could rapidly boil down the seawater to about 2 cups (right before the sodium chloride started to crystalize) and then transfer the brine to a wide baking dish to finish slowly dehydrating in a low oven. The result is a mix of chunky crystal sizes that provide a delicate, satisfying crunch. If you have access to clean seawater, I highly recommend trying this technique. Local, handmade flaky sea salt makes a great gift (for your mouth).

Photography by Steve Klise

Homemade Sea Salt

Why This Recipe Works