Add sugar and lime zest to a small plate. This is the same lime that you will be using to make your cocktail. Cut lime in half and wet rim of cocktail glass with lime juice. Dip rim into lime zest and sugar mixture. Set aside.
In a mixing glass, add lime juice from one whole lime, cherry syrup, and 4 pitted cherries. Muddle ingredients together. Add ice to your cocktail shaker and pour in contents of the mixing glass. Pour in vodka and give the shaker a good shake.
Add ice to your cocktail glasses and add an even of amount of your cocktail mix to each glass. Top off each glass with tonic water. Garnish with a cherry or citrus twist.