Across the board, bartenders are picking peppers to put a little pep in your sip. A jalapeño here, a Serrano there. But heat is a matter of taste! Capsaicin (measured in Scoville Heat Units, or SHU) varies greatly from harmless bells to the infamous Ghost Chili. Best you should read up on the hotness:
Jalapeño (2,500-8,000 SHU)
Mildly spicy right up front with a lingering flavor that is instantly recognizable. Ideal for muddling, infusions and garnishes. The heat is almost entirely in the seeds, so muddle slices whole but be sure to double-strain. Garnishes should always be seed-free.
Serrano (10,000-25,000 SHU)
An elegant, refined heat that sneaks up on you. Perfect for syrups and infusions (see recipe below), but again, the heat lies mainly with the seeds, which should be strained out or removed from garnishes.
Thai (Bird’s Eye) Chili (50,000-100,000 SHU)
The Thai chili (red or green) packs a whole lotta heat into a small but powerful package. Great for syrups; seeds are too small to make a garnish edible. Thai chilies love rum, tequila and Southeast Asian flavors such as lemongrass, ginger, lime and basil.
Habanero (100,000–350,000 SHU)
Use extreme caution when working with these firebombs! Just 3-5 drops of fresh habanero juice will turn five liters of simple syrup fiery. When working with habaneros, do so outside, if it’s not windy; wear gloves and protective eyewear. In carefully controlled amounts, habaneros perform well in syrups, with tropical nectars, coconut, chocolate and Caribbean and South American spirits such as rum, cachaça and pisco.