Make the ginger syrup: Blend the roughly chopped ginger with half the water. Add to a saucepan with the remaining water and sugar. Simmer for 10 minutes, then strain through cheesecloth and squeeze the ginger pulp well. Let the syrup cool completely.
Fill a glass with ice: Add enough ice to leave room for the ginger syrup and sparkling water.
Add the ginger syrup: Pour 2 tablespoons of chilled ginger syrup over the ice. Adjust to taste for a stronger or sweeter soda.
Add sparkling water: Slowly pour in the cold sparkling water and gently stir. Garnish with lime or lemon and serve immediately.
Notes
Use the nutrition card in this recipe as a guideline.