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 vibrant color.
03 - Pour mixture through a fine-mesh strainer into a heatproof pitcher, discarding the used flowers.
04 - While tea is still warm, stir in granulated sugar and honey or agave syrup if using. Continue stirring until completely dissolved.
05 - Allow tea to cool to room temperature, then refrigerate for at least 1 hour until thoroughly chilled.
06 - Fill glasses with ice cubes and fresh lime slices. Pour chilled hibiscus tea over ice and garnish with mint leaves if desired.