I love hibiscus iced tea, whether served plain or infused with mint, ginger or lime. So, it should come as no surprised that I was interested in Diana Kuan's recipe for hibiscus mint granita with rum (or hibiscus mojito granita), posted at her fabulous Appetite for China website. Not only does the recipe include hibiscus, mint and lime, but a granita sounded like a great way to cool off on a hot summer day.
I started by boiling 1/2 cup of dried hibiscus flowers and a handful of crushed mint leaves in two cups of water. After 10 minutes, I removed the saucepan from the heat, stirred in one cup of sugar until it dissolved, and let the mixture cool for about a half hour.
The hibiscus syrup was then strained into a large bowl or baking dish, and the hibiscus flowers removed, before adding the juice of one lime and 1/4 cup rum. In retrospect, it would have been better to add the mint at this stage; instead, I stood over the baking dish and picked out the hibiscus flowers with a fork, while doing my best to leave the damp mint leaves in.
The baking dish then went into the freezer, to be removed and stirred with a fork every half hour until an ice slush had formed. I dutifully followed these instructions, but because of the presence of the rum, ice did not even begin to form until three hours had passed. (As Kaun notes, the freezing stage will go more quickly if you omit the rum and make a virgin granita.)
While the recipe is simple, it ultimately took me seven hours to complete the granita, even though I divided the mixture between two baking dishes so that it would freeze faster. It's true that much of the seven hours was spent doing other things, while making sure that I could get to the freezer to stir the granita from time to time. However, there were points when I was tempted to just drink the partly-frozen hibiscus mojito, and forget about the granita part.
This recipe might be quicker you have a gelato or ice cream maker. If you are using the freeze-and-scrape method, and are including rum, you might want to give the granita several hours to freeze before scraping it.
Edited to add: Another method for getting around the rum-freezing problem: make the granita without the alcohol, then pour the rum over it before serving.