I'm not sure how it took so long for me to have my first Passionfruit Mojito. I've long made Passionfruit margaritas and often travel to places that have tons of the fruit (Hawaii, Mexico) but had never had the cocktail until Thailand. And while I was there, it was my go-to drink since almost every bar I visited had their own version. The best ones were made with lots of passionfruit so go ahead and add 1 or 2 or 3 passionfruit to one cocktail (if you can manage)!
or 1 tablespoon passionfruit puree
Combine the lime juice, sugar, all but 1 sprig of mint, and passionfruit in a cocktail shaker and muddle a few times to break up most of the mint and passionfruit seeds. Pour mixture into a tall glass (such as a Tom Collins), add ice to fill 3/4 of the way, stir then top with club soda, more ice (as needed), garnish with mint and serve.
You can do this in a sturdy Tom Collins glass too—just be careful you don't muddle too hard!