This drink is another from the Mai Kai in Florida, invented by Mariano Licudine in the late 1950s.
3 oz aged rhum agricole
0.75 oz lime juice
0.5 oz passionfruit syrup
0.25 falernum syrup
Combine all ingredients with a handful of ice, blend for 5 seconds and pour unstrained into a chilled rocks glass with more crushed ice.
The sip opens with a bit of lime and the tropical fruitiness of the passionfruit syrup. The lighter rhum agricole comes in first, then finishes with a blend of the falernum spices and the dry oak of the aged rhum agricole.
This is a very rhum-focused drink and you'll need something with a decent amount of age to make it work well. Either of the Neisson rhums pictured are a good choice. I made it with a 50/50 split to get a good balance between the fresher cane notes of the Élevé Sous Bois and the woodier Réserve Spéciale. You could also go with Rhum J.M. Élevé Sous Bois or VSOP or Clément VSOP.
For an interesting variation, you can also make a nice bourbon drink in this mold. Just swap out the lime juice for lemon and pick a whiskey with a healthy dose of oak in it, like Elijah Craig 12 Year or Eagle Rare Single Barrel. The spice notes from the falernum go well with bourbon and the result is quite balanced.