In a medium pot, add the hibiscus flowers, citrus zest, and water.
Bring to a gentle simmer, then turn off the heat and allow the mixture to steep for at least 30 minutes or preferably overnight for deeper flavor.
Once the mixture has cooled completely, strain it into a pitcher, discarding the solids.
Stir in the fresh citrus juice and your desired amount of sugar.
Serve chilled over ice.
For an extra special touch, rim your glasses with chamoy and Tajín before pouring.