Combine agave nectar and water in a small saucepan over low heat and stir until smooth and just warmed (do not boil). Add the dried ghost pepper pod (pierced once) or ghost pepper flakes, remove from heat, and let steep for 10–20 minutes depending on desired heat. Taste carefully (use a tiny spoon) and remove pepper when syrup reaches your preferred spiciness—remember it will concentrate in the cocktail. Strain through a fine mesh sieve or cheesecloth into a clean container. Cool before using. Refrigerate leftover syrup up to 2 weeks.

Rim & Glass

Prepare a shallow plate with the sea salt and mix in the powdered ghost pepper flakes very thoroughly (use gloves/avoid contact). Run a lime wedge around the glass rim and dip the rim into the salt-spice mixture, rotating to coat evenly. Set glass aside.

Cocktail Build

If using egg white: add egg white to a cocktail shaker and dry-shake (no ice) vigorously for 10–15 seconds to emulsify.

Add reposado tequila, Cointreau (or triple sec), fresh lime juice, yuzu/lemon juice, ghost pepper agave syrup, and ice to the shaker.

Shake hard for 12–15 seconds until chilled and well-aerated. If you used egg white, this second shake with ice will create a silky foam.

Double-strain the cocktail into the prepared glass over fresh ice (use a fine mesh strainer if you want a very clean drink).

Float the mezcal: gently pour 1/4 oz mezcal over the back of a bar spoon held just above the drink so it sits as a smoky layer on top.

Garnish

Garnish with a lime wheel on the rim and, if desired, a very thin slice of ghost pepper or a small fresh chile for dramatic effect. Serve immediately with a warning about heat if guests are unaware.