In a saucepan, combine the sugar with 560ml of water. Put the lid on the saucepan and bring the water to the boil over a medium heat.
Once boiling, remove the pan from the stove and add the ground coffee, whisking to remove any lumps.
Allow the coffee to brew for 1 minute, then strain through a paper filter or muslin to remove the coffee grounds.
Transfer the liquid to a sterilised bottle and allow to cool. Once at room temperature, add the vodka, mix and seal.
To create an Espresso Martini, simply shake 120ml of the syrup with ice and strain into a Martini glass.
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