The mojito is an essential summer cocktail: Rum, mint, lime juice and a hit of spritzy soda water—it doesn’t get any better. But it can get clearer. 

By Justine Sterling
Updated May 23, 2017

The mojito is an essential summer cocktail: Rum, mint, lime juice and a hit of spritzy soda water—it doesn’t get any better. But it can get clearer. At Bourbon Steak DC in Washington, DC, head bartender Duane Sylvestre is making a crystal-clear mojito that looks just like a mint-laced glass of water. The secret: clarified lime juice.

Sylvestre got the idea from the mad mixology scientist Dave Arnold, of New York City’s Booker and Dax, who wrote about the process on his blog, Cooking Issues, back in 2009. After fruitless attempts to clarify citrus juices using vacuum bags and centrifuges, Arnold came up with a simpler and much more effective method: Whisk agar (a powdered gelatin obtained from sea vegetables) into a heated portion of juice, mix that into more juice, then cool the mixture in the fridge or an ice bath until it’s set, then strain. The agar grabs onto the suspended solids that color the liquid, leaving you with a crystal clear liquid and a soft gel the color of the original juice.

There are a few reasons you should clarify lime juice (or any other citrus juice). First of all, by removing the solids, you slightly raise the acidity of the juice, which helps increase shelf life. Second, clarified lime juice won’t froth up when mixed with soda water, like regular lime juice will. That’s because there are no particles for the CO2 to cling to, which is what causes it to froth over. (Think about adding sparkling wine to a mimosa and how much easier and more efficient it would be if you didn’t have to stop and wait for the bubbles to subside before adding more wine.) Thirdly, and most importantly, it looks cool.

“Mojitos are commonplace,” says Sylvestre. “It’s like a vodka soda or a rum and Coke—you don’t even think about the drink that you’re drinking. But this version looks like a glass of water with a mint leaf floating in it. It tastes like a mojito but it’s not green and it’s not cloudy from the lime juice. It’s fun again.”

In order to avoid any coloration from the mint, Sylvestre presses the mint into the rum rather than muddling it, then strains it out. “You just want to release the aromatics,” he says. “Obliterating the rum makes the cocktail bitter.”

Clarifying lime juice at home is easy—agar is fairly cheap and widely available—though you do need a kitchen scale, since the recipe Sylvestre works with is in grams. Here, his simple method for clarified lime juice:

Start with 1,000 grams of fresh lime juice and 2 grams of agar. Dissolve the agar in 200 grams of heated lime juice then temper that mix back into the remaining lime juice. Put the juice into an ice bath until it becomes the consistency of what Sylvestre calls “soft-serve Jell-O.” Set a fine strainer over a bowl and pour in the gel. Discard the gel, save the remaining clear liquid.