Muddle the Mint: In a sturdy glass, add the 3 mint leaves and simple syrup. Use a muddler or the back of a spoon to gently press the mint leaves against the glass to release their flavors. Be careful not to shred the mint.

Add Lime Juice and Limoncello: Pour the lime juice and limoncello over the muddled mint mixture. Stir to combine all the flavors.

Add Rum: Pour the white rum into the glass. Stir well to integrate all the ingredients.

Add Ice: Fill the glass almost to the top with ice cubes.

Top with Soda Water: Slowly pour the soda water over the ice. Stir gently from the bottom to the top of the glass to mix all the ingredients evenly.

Garnish and Serve: Garnish with additional mint leaves. Optionally, you can also add a slice of lime or lemon on the rim of the glass for an extra touch.