- 1/2 lb fresh rhubarb stalks, cut into 1/2-inch pieces (10 cups)
- 2 1/2 cups cold water
- 1 3/4 cups sugar
- 3 tablespoons coarsely chopped peeled fresh ginger
- About 2 cups sparkling water
- Bring rhubarb, cold water, sugar, and ginger to a simmer in a 4- to 5-quart pot over moderate heat, uncovered, stirring once or twice, then simmer 1 minute. Remove from heat and let steep, uncovered, 1 hour.
- Pour mixture through a large fine-mesh sieve into a large bowl, gently stirring but not pressing on solids (discard solids; you will have about 6 cups syrup). Chill syrup completely, about 45 minutes.
- Serve syrup in glasses over ice with a splash of sparkling water.