I make Pati's recipe, too. The concentrate will keep at least 3 months in the fridge.
To use the concentrate to make a drink, dilute 1 cup of the concentrate with 3 to 4 cups of water, or to taste, and pour over ice. You can also mix this with iced tea, limeade, or lemonade to add a gorgeous color and flavor.
Other uses for Jamaica (pronounced ham EYE ee kah) concentrate include meat marinades, fruit sorbets or popsicles, and vinaigrette dressings.
You can find the dried hibiscus flowers at groceries that cater to Latino customers.