1Cool the syrup — Let the cherry syrup cool completely.
2Strain the syrup — Strain the cooled cherry syrup.
3Combine the ferment — Add the syrup and ginger bug to a fermentation-safe bottle, then top it off with water.
4Ferment the cola — Leave the bottle to ferment until it develops carbonation, about a day.
5Chill before opening — Place the bottle in the fridge for at least 24 hours before opening. This slows fermentation and helps calm the pressure inside the bottle.