If you want a salted rim, rub the lime wedge around the outside rim of a highball or Collins glass (or coupe for a shorter pour). Dip the moistened rim into a shallow plate with the teaspoon of salt to lightly coat. Set the glass aside.

Muddle cilantro and agave

In a cocktail shaker or mixing glass, add the 8 cilantro leaves and 0.5 oz agave syrup. Gently muddle 6–8 times just to bruise the leaves and release bright herb oils — avoid pulverizing to prevent bitterness.

Add juices and rum

To the shaker, add 4 oz pineapple juice, 0.5 oz fresh lime juice, and 1.5 oz white rum (omit to make a mocktail). Fill the shaker with ice until about 3/4 full.

Shake

Secure the shaker lid and shake vigorously for 10–12 seconds until the outside of the shaker feels cold (this chills and slightly dilutes the mix).

Strain over fresh ice

Fill the prepared glass with fresh ice (about 1 cup). Double-strain the shaken mixture into the glass using a fine mesh strainer over a Hawthorne or into the glass to catch cilantro bits for a cleaner texture. Leave room at the top for tonic.

Top with tonic

Gently pour 3 oz chilled tonic water over the back of a spoon or down the side of the glass to preserve carbonation and create a layered look. Stir once gently with a bar spoon to integrate.

Garnish and serve

Garnish with a sprig of cilantro and a pineapple wedge on the rim. Serve immediately with a straw. Taste and, if needed, add a small splash (0.25 oz) more agave for sweetness or a squeeze of lime for brightness.