Recipe

Homemade Sea Salt

by Dan Souza

After working on our feature story “Salt Life,” a deep dive into the surprisingly complex world of salt, I had to try my hand at making my own sea salt. 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

Yield
Makes about 100 grams (½ cup) sea salt
Ingredients
3,950 g clean seawater
450 g water (if needed)
158 g Diamond Crystal kosher salt (if needed)
4 quarts clean seawater
2 cups water (if needed)
5½ ounces Diamond Crystal kosher salt (if needed)
Essential Equipment
Instructions
    • 3,950 g clean seawater
    Strain water through coffee filter into large enameled Dutch oven. Bring to boil over high heat. Boil water until fine white sediment forms on bottom of pot and water measures about 530 grams (2 cups), 1 to 1½ hours. (If you don’t see white sediment form, simply stop boiling at 530 grams (2 cups) and proceed to step 2.)    
  2. Adjust oven rack to middle position and heat oven to 300 degrees F/150 degrees C. Transfer water to bowl or liquid measuring cup and let sediment settle for 5 minutes. Gently pour clear brine into 13 by 9-inch baking dish, being careful to leave sediment behind; discard sediment. Transfer dish to oven and bake until brine fully crystallizes, about 1½ hours. Let salt sit until cool enough to taste. Taste salt. If salt tastes great, gently scrape up salt with metal spatula and transfer to airtight container. (Salt can be stored indefinitely.) If salt is bitter, proceed to step 3.  
    • 450 g water
    • 158 g Diamond Crystal Kosher Salt
    Whisk water and salt in bowl or liquid measuring cup until salt dissolves, 1 to 2 minutes. (A very small amount of salt may remain undissolved at bottom of bowl.) Using metal spatula, gently scrape up crystallized salt from dish and transfer to medium bowl (rinse and dry baking dish). Pour brine over salt, being careful to leave behind any undissolved salt. Gently stir for 30 seconds. Drain salt in fine-mesh strainer and discard brine. Transfer salt to rinsed and dried baking dish. Return to oven until fully dry, about 45 minutes. Let salt cool completely. Gently scrape up salt with metal spatula and transfer to airtight container. (Salt can be stored indefinitely.)    
Instructions
    • 4 quarts clean seawater
    Strain water through coffee filter into large enameled Dutch oven. Bring to boil over high heat. Boil water until fine white sediment forms on bottom of pot and water measures about 2 cups, 1 to 1½ hours. (If you don’t see white sediment form, simply stop boiling at 2 cups and proceed to step 2.)    
  2. Adjust oven rack to middle position and heat oven to 300 degrees F/150 degrees C. Transfer water to bowl or liquid measuring cup and let sediment settle for 5 minutes. Gently pour clear brine into 13 by 9-inch baking dish, being careful to leave sediment behind; discard sediment. Transfer dish to oven and bake until brine fully crystallizes, about 1½ hours. Let salt sit until cool enough to taste. Taste salt. If salt tastes great, gently scrape up salt with metal spatula and transfer to airtight container. (Salt can be stored indefinitely.) If salt is bitter, proceed to step 3.  
    • 2 cups water
    • 5½ ounces Diamond Crystal Kosher Salt
    Whisk water and salt in bowl or liquid measuring cup until salt dissolves, 1 to 2 minutes. (A very small amount of salt may remain undissolved at bottom of bowl.) Using metal spatula, gently scrape up crystallized salt from dish and transfer to medium bowl (rinse and dry baking dish). Pour brine over salt, being careful to leave behind any undissolved salt. Gently stir for 30 seconds. Drain salt in fine-mesh strainer and discard brine. Transfer salt to rinsed and dried baking dish. Return to oven until fully dry, about 45 minutes. Let salt cool completely. Gently scrape up salt with metal spatula and transfer to airtight container. (Salt can be stored indefinitely.)    
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