The hibiscus syrup makes this a beautiful colour, it is cooling and refreshing and lets the flavour of the tequila come through. Look for 100% blue agave tequila it makes all the difference to your taste buds and your head the day after.
Firstly make the hibiscus syrup by putting the sugar and flor de Jamaica in a small sauce pan, stir, bring to the simmer until syrupy and the bubbles look like glass (approx. half an hour). Leave to cool, then decant into a container and refrigerate.
When ready to make the margaritas, put all the ingredients into a cocktail shaker and shake until your hands freeze to the metal. Pour into a glass and drink immediately!