Rinse the dried hibiscus flowers under cold water to remove any dust or impurities.

In a medium saucepan, combine the 4 cups of water (for boiling) and the rinsed hibiscus flowers. Bring the water to a boil over medium-high heat.

Once boiling, reduce the heat to low, cover, and let it simmer for 10-15 minutes. The water will turn a deep red color.

Remove the saucepan from the heat and let it steep for another 10 minutes to allow the flavors to intensify. Do not press the flowers during steeping, as this can release bitter notes.

Carefully strain the hibiscus mixture through a fine-mesh sieve into a heatproof pitcher or jar, pressing gently on the flowers to extract all the liquid. Discard the spent hibiscus flowers.

Add the 4 cups of cold water (for diluting) and the agave syrup to the strained hibiscus concentrate. Stir well to combine and ensure the agave is fully dissolved.

Taste and adjust sweetness as needed. Allow the Agua de Jamaica to cool completely, then refrigerate for at least 2-3 hours, or until thoroughly chilled.

Serve over ice, garnished with lime slices, orange slices, or a sprig of mint, if desired.