Lemonade has plenty of zip, but there’s always room for a touch more zing, and what’s zingier than the fiery heat of chiles? I’m not the first person to think that spicy lemonade is a good idea, and I sure won’t be the last. But I might be the first to come up with this particular method for making it—and the method makes a heck of a lot of sense once you understand the science.

There are several obvious ways to make a lemonade spicy. Some people spike the lemonade with a spicy chile powder, but while I don’t mind chile powder on the rim of the glass as a garnish, it muddies up the lemonade both flavor-wise and texturally. Others seem to think adding hot sauce is a good idea, but the vinegar kick of something like Tabasco or Cholula isn’t what I want competing with the fresh citrus acidity of lemon. Another approach is to infuse the lemon juice with chiles either via a long steep or by muddling the chiles in a glass with the juice. That works, but it fails to take advantage of a key fact: The capsaicin in chile peppers that makes them spicy is primarily fat- and alcohol-soluble, which makes lemon juice a less effective medium for extracting it.

But…how do we use fat to hold and distribute the capsaicin in a drink that’s made only from water, lemon juice, and sugar? Ah, so that’s where my technique comes in.

The Key to Extracting Capsaicin for Spicy Lemonade

The secret to getting the most out of our chile peppers can be found in a substance called oleo-saccharum, which more or less means “oily sugar.” It’s a frequent ingredient at cocktail bars, used to add the bold flavor of lemon to drinks in the form of a sugar syrup instead of tart juice. That’s because the lemon flavor in oleo-saccharum comes from the peel, not the juice, and as anyone who’s spent time with a lemon before knows, a lot of that essential lemon flavor and aroma is locked in the oils of the peel, not the juice.

By muddling and macerating lemon peels in sugar, the oils are drawn out along with water from the peel. This dissolves the sugar slowly until an emulsified lemon-oil syrup forms. It’s not a new technique to Serious Eats, nor is it a new technique to our lemonade recipes: Stella Parks published her recipes for a kind of quick-and-easy oleo-saccharum in which the peel is not even separated from the pith, which she uses to make both lemonade and limeade.

My little innovation was to build on this with the realization that I could take advantage of the lemon oils extracted during the oleo-saccharum formation to also dissolve the capsaicin from the chile peppers. There’s an old culinary saying that “fat equals flavor,” and that is absolutely true here. As a great conveyor of so many flavor molecules, from the lemony limonene of the citrus peel to the capsaicin of the chiles along with all the fruity chile flavors, the oil in this chile-lemon syrup is a powerhouse of flavor.

The Steps to Perfect Spicy Lemonade

The process for making this lemonade is the same as for our ultra-flavorful lemonade, just with the addition of chiles:

1. Juice the citrus and mince the chiles.
2. Macerate the juiced citrus halves with the chiles and sugar for a few hours to create the lemon syrup.
3. Mix a portion of the reserved lemon juice into the macerating fruit to “wash” the syrup off the fruit and create a spicy lemonade base.
4. Prepare amazingly spicy and refreshing drinks by adding the base to glasses with ice and diluting to taste with water.

It takes a bit longer than just juicing citrus and mixing that with sugar and water, but it’s significantly more flavorful this way. Plus, you’ll get the most bang for your chile-pepper buck, with a deeply fruity flavor profile and clean spice is perfectly integrated into the drink.

The Secrets to Chile Pepper Success

The trickiest thing about developing this recipe is that chile peppers can range quite a bit in their heat level, and an individual’s tolerance for heat is highly variable too. For this recipe, I chose red chile peppers because I want that ripe fruit flavor to meld with the lemons, not the raw, grassy-green flavor of jalapeños or Serranos. But even in the world of red chiles, you have a lot of options.

The quantities I’ve listed here worked well with medium-hot red finger chiles, which are often sold in Asian markets, though other medium-hot chiles like cayenne peppers can work too, as can red jalapeños. Small red chiles like Thai bird’s eye pack a bigger punch, so if you’re using those you’ll want to dial back the quantity, unless you really, really like heat.

My advice for getting the heat where you want it is, when in doubt, to start with a lesser amount; then taste the syrup as it’s forming, adding more chiles and letting them steep longer to draw out their heat—the syrup can go for up to 12 hours, so you have time. Keep adjusting as needed until you begin to detect the heat level you’re after and giving them enough time to infuse before straining.

One final note: In my tests, I found that I got the best flavor and heat from the chiles when I minced them quite finely, maximizing surface area for flavor extraction. You could also muddle them, smashing the chiles’ cells open. Large pieces of chile, though, just won’t do much, so make sure you mince or smash to get that flavor out.