01 - Bring water to a boil in a medium saucepan over high heat.
02 - Remove saucepan from heat and stir in dried hibiscus flowers. Cover and let steep for 10 minutes to extract full flavor and color.
03 - Pour the mixture through a fine-mesh strainer into a heatproof pitcher. Discard the spent hibiscus flowers.
04 - Add sugar and honey or agave syrup while tea is still warm. Stir continuously until completely dissolved.
05 - Allow tea to reach room temperature, then refrigerate for at least 1 hour until thoroughly chilled.
06 - Fill glasses with ice cubes and lime slices. Pour chilled hibiscus tea over ice. Garnish with fresh mint leaves if desired and serve immediately.