2) Remove from the heat and set aside to steep for 30 mins. Sieve and refrigerate until chilled.
For the cocktail:
1) Combine the tequila, 475ml of hibiscus syrup, lime juice and orange liqueur in a large jug. (The vampiro can be made up to this point a day ahead and refrigerated.)
2) To serve, fill a cocktail shaker half way with ice, add the some of the vampiro and shake until chilled. Strain and serve straight-up in a cocktail glass garnished with lime slices. Alternatively, serve over ice in a rocks glass.
Cook's Note: Hibiscus flowers can be found in most Latin markets and maybe labelled by its Jamaican name West Indian sorrel.