Put the sugar and water in a saucepan and heat until the sugar has dissolved.
200 g sugar, 250 ml water
When it has cooled a bit, add the lime juice and zest. It is added when the syrup has cooled as adding it to boiling hot syrup will alter the flavour of the lovely fresh zest and juice.
Sterilise a bottle or jar by running it through the dishwasher, washing in hot water and drying well or warming in the oven
Pour the syrup into the bottle or jar and store in the fridge
Notes
Keep the lime carcass to use in making lemon peel jam