Pull two fresh espresso shots (about 2 ounces) using an espresso machine or moka pot, ensuring the shots are served within 30 seconds of extraction.

Fill a tall glass (10-12 ounces) nearly to the top with ice cubes to keep the drink cold without over-diluting.

Pour 4-5 ounces of chilled tonic water into the ice-filled glass to minimize foam and maintain carbonation.

Stir in 1/2 teaspoon of simple syrup or agave nectar if a sweeter flavor is desired.

Slowly pour the espresso shots over the tonic and ice to create a layered visual effect.

Gently stir the drink three to four times with a bar spoon to combine flavors while preserving carbonation.

Twist a lemon or lime wedge over the glass to release citrus oils, then drop it in as a garnish.

Taste and adjust the ratio of tonic or espresso to suit your personal preference before serving.