Bring 4 cups of water to a boil in a medium saucepan over high heat. Once boiling, remove from heat and add the dried hibiscus flowers.
Steep the hibiscus flowers for exactly 10 minutes, covered, to extract the deep color and floral flavor without bitterness. The liquid should turn a rich ruby red.
Strain the hibiscus liquid through a fine-mesh sieve into a large pitcher, pressing gently on the flowers to extract all the liquid. Discard the spent flowers.
While the hibiscus base is still warm, stir in the honey until completely dissolved. Let the mixture cool to room temperature, about 30 minutes.
Once cooled, add the fresh lemon juice and 2 cups of cold water. Stir well to combine all the flavors evenly.
Refrigerate for at least 1 hour until thoroughly chilled. The flavor will develop and deepen as it sits.
Taste and adjust sweetness or tartness if needed by adding more honey or lemon juice. Serve over ice with lemon slices and mint sprigs if desired.
