The ridiculous price of limes may indeed be Limepocalypse for bars and restaurants, but for the home and party bartender mixing tropical and Mexican cocktails, it is Revelation. The simple truth is that any drink made with rum or tequila tastes so much better when mixed with Key lime juice.
This happy relationship has to do with the source of these spirits. Rum, tequila and Brazilian cachaça are derived from fermented plants (sugar cane and blue agave), and the tart acidity of Key lime juice brings out these flavors better. Most of the other liquors we use -- whiskey, vodka, gin and liqueurs -- are derived from grains, so European and American cocktails taste better with regular limes, which are known as Persian or Tahitian limes.
I've tested Key limes vs. Persian limes in 34 common cocktails that use lime juice to mix, or a lime wedge as a flavor component, and this rule holds fast, with only one exception, which I'll get to in a minute.
The reason Key lime juice is rarely used in bars, and why Key limes are still cheap, is that they're labor-intensive. I used to rely on a yellow lemon squeezer to do lemons and limes, but Key limes require a small green squeezer. I found an effective $4.99 Alpine squeezer at Fiesta, along with still-low-priced Key limes, which are also known as Mexican limes.
Key limes have small seeds that can slip through the squeeze holes, so it's best to squeeze them through a small sieve. Also, more juice can be squeezed out of the limes if the fruit is warmed up to room temperature. Each lime yields about 1/4 ounce of juice, so you'll need three for every margarita.
The Exception to the Rule
Vodka and tonic is technically a tropical drink, descended from the gin and tonic. The original cocktail was devised by the British East India Company to defeat tropical malaria with the active ingredient of quinine. It's the quinine that blends well with Key lime juice.
I use Tito's Handmade Vodka, not because it's Texan like me, but because this vodka brings out the taste of fresh lemon or lime better than most vodkas. I don't know the reason -- organic chemistry isn't my thing -- but I think it has something to do with the vodka being distilled from corn rather than wheat, rye or potatoes.
Vodka & Tonic
- 2 ounces Tito's Handmade Vodka
- 3 ounces Fever-Tree Mediterranean Tonic
- ½ of a Key lime
-- Fill a highball glass with ice. Pour in the vodka, and listen for the ice to crackle. Add the tonic. Squeeze in the juice from the Key lime half, and drop it in for garnish.
Canada Dry Tonic also works well in this cocktail. If you use a Persian lime wedge, it will fail, but with a Key lime the drink will be refreshing.