This Is What the World’s Cleanest Martini Tastes Like

Is there anything Iceland isn't good at? It's the best country on earth to be a woman, a powerhouse of geothermal energy, home to delicious yogurt-cheese hybrids …

And now, after 11 years of trying, it may also have made one of the purest vodkas in the world. Perhaps even THE purest vodka in the world.

The Icelandic weren't deliberately slow on the spirit uptake. Prohibition was only lifted enough to allow for the production of a kind of aquavit known as "black death" there in 1935 and you couldn't drink beer until 1989. It wasn't until 2004 that the first vodka distillery was built on the island.

And not a moment too soon. It turns out that the volcanic lava rock from which Iceland is made comes in very handy with spirit production. Christened Reyka (meaning "steam or smoke" in honour of the island's geothermal energy), Iceland's first vodka is both incredibly pure and sustainable to produce.

In fact, London bartender Joe Petch was so impressed by Reyka's purity, that he set about using it to make the cleanest martini possible.

I'm holding the result of his labours in my hand as he tells me this story. We're standing 24 floors up in City Social, Petch's central London bar with an impressive view out over the city. The grey buildings and sludgy Thames laid out beneath us couldn't be further removed from the clarity of what's in my glass.

Petch tells me that Reyka all begins with the right raw ingredients.

"It starts with clean water," explains Petch. "Clean water is essential for clean-tasting spirit. And clean air too."

The Reyka distillery was founded on a spot near the town of Borganes, north of Reykjavik and a sweet spot for air quality.

"The distillery uses water that's naturally filtered through pure lava rock," says Petch.

That water comes from the Grábrók springs, considered among the purest in the world. It is mixed with raw grain spirit in a vodka still—but not just any old still.

"The vodka's made with a rare type—the Carter-Head still," explains Petch. "It was originally designed to purify spirits and then infuse them with botanicals for gin."

There are only six Carter-Head stills in the world, and Reyka are the only company to use it for vodka. As the spirit evaporates and is pushed through the still's neck, it gets forced through a second chamber. If you were making gin, this would be where the liquid becomes infused with the necessary botanicals.

"Instead of plants, Reyka put lava rock in the still," explains Petch. "It adds an extra layer of filtration to make the vodka as smooth as possible."

The result tastes incredibly, well—clean. There's none of that Have-I-just-swallowed-paint-stripper-by-accident? feeling on the back of your throat, Reyka is a supremely smooth drink.

It's also more eco-friendly than your average vodka. No charcoal is needed for the purification of Reyka (and therefore, no burning of trees) and any electricity used comes straight from the ground. I'm beginning to understand how Iceland might lay claim to making the world's purest vodka.

Petch stayed in Iceland to source the ice required for his cleanest-martini-possible mission, not wanting to sully the spirit with inferior water. This time, he looked to the Ölfus Spring.

"The spring was formed over 5,000 years ago as the result of a massive volcanic eruption," Íris Jóhannesdóttir from the Icelandic Glacial water company tells me. "The pristine lava rock left the spring with its own natural filtration system. The water is so pure that nothing needs to be added or taken away. It has exceptional balance, low mineral content, and a naturally alkaline pH of 8.4."

Petch had found the makings of his ice. As any good water sommelier might tell you, the mineral content of water affects taste, balance, and the character of water.

"Tap water is known to contain heavy metals, pesticides, and chemicals," adds Jóhannesdóttir. Of course, it's perfectly safe to drink tap water, but if you're in pursuit of the purest possible vodka martini, it's not going to help the flavour profile.

"It means our water tastes smoother, crisper, and silkier," she says.

On the bar at City Social is a solid slab of ice made from this water. It's about a foot thick, but is so clear that you could be looking through half a millimetre of glass.

With vodka and ice sorted, Petch tells me about the vermouth component of his clean martini.

"Lillet Blanc was the only option," he says. "Its grapefruit-y flavours compliment the slight aniseed taste in the vodka."

It's the only non-Icelandic ingredient in Petch's Martini, but he tells me he considers it one of the best vermouths.

Still, he uses it extremely sparingly. Decanted into mini-pressurised cans like a perfume sample, Petch merely spritzes the martini glass with the vermouth—two sprays—before pouring in the vodka, which is carefully cooled by being stirred with crystal-clear ice. With another final few sprays and a twist of grapefruit zest, the drink is complete.

In spite of its Icelandic origins, this is a martini that would make Winston Churchill—who famously liked his martinis so dry that he'd merely wave the bottle of vermouth over the top of his glass—extremely proud.

Sipping it on this dreary London day, I wonder if Petch would ever consider using Reyka and his specially sourced Icelandic ice to make the cleanest dirty martini in the world.

He looks pretty horrified at the idea.

"This drink is at the complete opposite end of the spectrum from a dirty martini," he says. "You wouldn't want to add brine to something as pure as this. If you're going to spoil it with brine, you might as well use water from the Thames for that."

The thought makes me shudder. Iceland might be cold and volcanic, but I'll take its vodka—stirred in ice with a Churchillian hint of vermouth—any day.