Step 1

Add the syrup and mint leaves to a highball glass and gently muddle.

Step 2

Pour the rum and lime juice into the glass and top the mixture with ice. Pebble ice is preferred, but not mandatory.

Step 3

Gently churn the mixture with a bar spoon or swizzle stick, then top with club soda.

Step 4

Add more ice, if necessary, then garnish with a sprig of mint.