In a medium saucepan, bring 4 cups of water to a boil. Once boiling, add the dried hibiscus flowers and reduce the heat to a simmer. Let it simmer for about 15 minutes.

Remove the saucepan from heat and strain the hibiscus tea through a fine mesh sieve into a large pitcher, discarding the flowers.

While the tea is still warm, stir in the granulated sugar until fully dissolved.

Add the fresh lime juice to the pitcher and mix well.

Pour in 4 cups of cold water and stir to combine. Taste and adjust sweetness if necessary by adding more sugar or lime juice.

Chill the hibiscus limeade in the refrigerator for at least 1 hour before serving.

Serve over ice cubes and garnish with lime slices and mint leaves.