By NANCY ANDRUM

From the outside, Midge Jolly’s newest salt house looks like an igloo that went long instead of domed. Inside, though, a block of ice wouldn’t stand a chance.

"Actually some friends have asked us if we’ll lend it out as a sauna," Jolly says. "It can get to 149 degrees in there in the middle of the day."

Perfect for producing buckets of sweat and, in about a month’s time, 40 quarts of sea salt.

Jolly and her husband, Tom Weyant, are the founders of Florida Keys Sea Salt. It’s selling in the Keys and has been purchased wholesale (though not yet offered retail) by The Meadow (www.atthemeadow.com), an online gourmet store that sells nearly 100 salts from around the world.

‘That virgin batch was ugly’

Jolly and Weyant have four salt houses on their property on Sugarloaf Key, the newest 32 feet long, 12 feet wide and 6 feet tall. White plastic sheeting arches over the top, and each end is covered in small-gauge mesh to keep out the bugs ("biologicals" Jolly calls them) and facilitate evaporation.

Two long, shallow troughs, called pans, run the length of the structure, each of which holds 240 gallons of seawater – about three bathtubs’ worth – from nearby Bow Channel.

After 26 days of evaporation, there was the first hint of salt – fine grayish crystals. In another 10 days or so, when the water has almost completely evaporated, Jolly will scrape up snow-white crystals with her favorite low-tech tool.

"I will bring out a squeegee," she says. "I spent lots of time figuring that out. I used to use spatulas."

She and her husband still are figuring out a lot of things, Jolly says.

"We’ve been at it now in prototype and testing for a long time. But all of a sudden, the thing’s in production, which we weren’t before, so it seems to outsiders we’re knowledgeable."

An early lesson: You can’t make sea salt in a lobster pot.

"That virgin batch was ugly, and it really didn’t taste good. I had seen an interview with a Scottish chef. Being of Scottish descent myself, I was especially interested. I thought, ‘If he can do that, I can do that.’

"We went and got three gallons of water and put it on the stove and cooked and cooked and cooked and – oh my gosh, we cooked forever.

"It got down to this gray sludgy stuff that was just muddy and yucky. I think I took a bath in it," she says with a laugh. "I assure you, we did not eat it."

A link between the Keys’ past and future

But they read volumes, they consulted a University of Florida expert, they got help building the salt houses and, suddenly, they’re salt farmers.

Jolly sees their endeavor as a link between the Keys’ past and future. In the early 1800s, salt making was a major, and lucrative, industry in the Lower Keys. Natural salt pans lined the eastern edge of Key West, and Bahamian laborers, who had the expertise, made industrialists wealthy.

Everything old is new again, and a blizzard of artisan salts – brick red from Hawaii, dove gray from Brittany, baby-girl pink from Australia – attests to the booming popularity of the ancient craft.

When Jolly and Weyant started, however, survival was the priority. She had been a midwife, but the number of home births in their community declined, and she joined her husband’s landscaping business.

In 2005, though, the business sank.

"When Hurricane Wilma came and brought, we think, 13 feet of water under our house, she also brought lots of salt with her and turned our landscaping business upside down," Jolly says. (Fortunately, the house rests on 14-foot stilts.)

Salt becomes the salvation

In 2006, they founded their new business, and salt became their salvation.

The look and the feel of each batch that Jolly harvests varies depending upon the time of year, the temperature and whether any rainwater resoaked the salt.

"I don’t really know how to identify our spring salt other than it has the giant crystals that form really fast, or the trace mineral salt, which is wet and a little grayish – a classic sea salt gray – or the sulfur salt, which comes from our well, and that has a reddish-gold tint to it."

And the taste?

Ana Machado is an assistant professor at Johnson & Wales University in North Miami. One of the first things to which she introduces her incoming students is salt – not the salt they think they know, but a diversity of salts from around the world.

She tasted a couple of types of Florida Keys Sea Salt, sampling Winter Solstice first. It has a relatively small crystal because the water evaporated slowly:

"It’s not intense as the other one, lighter; you feel the flavor of the saltiness and then it’s mellow all the way," Machado says.

Though salt is the most tangible result of Jolly’s efforts, she says she is harvesting something more precious.

" Wilma’s watery rush through here brought Florida Keys Sea Salt to us, and I see it as a way that we will be able to stay in our home and stay in the Keys where our children were born."

Spinach-Shiitake Gratin with Sea Salt

Serves: 4

1 tablespoon extra-virgin olive oil

4 ounces shiitake mushrooms, stems trimmed, caps sliced about 1/4 inch thick

1 pound cleaned baby spinach leaves

3 two-finger pinches sea salt

3 grindings black peppercorns

2 tablespoons dry sherry

1 cup heavy cream

2 teaspoons Dijon mustard

Grated nutmeg

2 ounces shredded Gruyere cheese

Heat a broiler. Heat the olive oil in a very large skillet over medium high heat. Add the mushrooms and saute just until tender, about 4 minutes. Add the spinach leaves and stir until completely wilted, about 3 minutes. While the spinach is cooking, season it with one pinch sea salt and freshly ground pepper. Transfer to a shallow gratin dish or casserole.

Return the pan to the heat, and add the sherry. Bring to a boil. Add the cream, and boil until the volume is reduced by half. Remove from heat and stir in the mustard and nutmeg. Pour over the spinach and spread evenly.

Scatter the Gruyere on top of the spinach mixture and run under the broiler until the cheese is fully melted and a little brown. If it begins to get oily before it browns, remove it right away. Scatter the remaining sea salt over top and serve immediately.

Note: Florida Keys Sea Salt sells for $6 to $7.50 an ounce plus shipping, depending on the variety. You can see pictures of the various types at www.floridakeysseasalt.com and request an order form by calling (305) 745-4098 or emailing floridakeysseasalt earthlink.net.

Recipe adapted from www.saltnews.com.