01 -  In a large saucepan, bring the water to a boil. 
 02 -  Add hibiscus petals, ginger slices, cloves, cinnamon sticks, and allspice berries. Stir to combine. 
 03 -  Remove from heat. Add orange and lemon slices. Cover and let steep for at least 2 hours, or until the mixture is deeply colored and fragrant. For a stronger flavor, steep overnight in the refrigerator. 
 04 -  Strain the mixture through a fine sieve or cheesecloth into a large pitcher. Discard solids. 
 05 -  Stir in the sugar until fully dissolved. Taste and adjust sweetness as desired. 
 06 -  Chill until very cold. Serve over ice, garnished with extra citrus slices if desired.