01 - Bring 4 cups of water to a boil in a medium saucepan over high heat.
02 - Remove saucepan from heat. Add dried hibiscus flowers, cover, and let steep for 10 minutes to extract full flavor and deep red color.
03 - Pour the mixture through a fine mesh strainer into a large pitcher. Discard the used hibiscus flowers.
04 - While the tea is still warm, stir in the granulated sugar until completely dissolved. Add honey or agave syrup if using, stirring to incorporate.
05 - Pour in the fresh lime juice and 3 cups of cold water. Stir thoroughly to combine all ingredients.
06 - Refrigerate the pitcher for at least 1 hour to allow flavors to meld and tea to reach optimal serving temperature.
07 - Fill serving glasses with ice cubes. Pour the chilled hibiscus tea over ice. Garnish each glass with fresh lime slices and mint leaves before serving.