To make the rosemary syrup; add the same amount of water and sugar (1 cup each) into a saucepan, add a few sprigs of fresh rosemary and bring to the boil.
When the sugar is dissolved the syrup is ready. Take out the rosemary and allow the syrup to cool.
Fill a glass with crushed ice, add all ingredients and stir well to combine.
Notes
You can also add some thyme for extra flavour.
Don’t let the sugar syrup caramelize, it should stay colourless.