Serious Eats: Recipes
Falernum can be tricky to find commercially, but it's easy to make at home so that you can be ready to mix up lots of classic Tiki cocktails.
I kept it pretty simple, but you could use an overproof rum or include ginger, star anise, cinnamon, or lemon zest. If you want to do it syrup style, you could skip the rum altogether and just flavor a simple syrup.
I left the ginger out, because I think it takes over the flavor. However, many consider it a part of the traditional recipe. You can add a tablespoon of grated ginger with the lime zest, if desired. Falernum is best used within a month, and does not need to be refrigerated.