12 oz. pkg. frozen raspberries
2 c. sugar
1/2 c. water
4 tea. grated zest and 1/2 c. juice from 4 limes
chilled club soda (I used 7up- the club soda was a bit too bland)
Heat raspberries, sugar, and water in saucepan over medium heat about 5 minutes. Mash berries with a potato masher or whisk, then stir in lime zest & juice. Simmer until slightly thickened, about 5 minutes.
Pour raspberry mix through fine sieve. You'll end up with a little more than 2 1/2 c. syrup. Discard solids. Refrigerate syrup until cool- 30 minutes (it will keep up to 1 week)
To serve, combine 3/4 c. soda and 3 tbl. syrup into a tall glass with ice.
For larger servings, 1 liter of soda will take about 1 1/2 c. syrup.