Combine all ingredients in a glass with ice, top with soda water and stir!
Combine pineapple, tarragon and water in saucepan and bring to a boil at 220 degrees. Once it starts to boil, immediately lower temp and simmer for 10 minutes. Remove from heat and strain through mesh strainer. Pressing to extract juice. Run this juice through a coffee filter. Add pineapple juice to clean pot and bring back to boil. Add sugar while it heats up and cook until fully dissolved. Allow to cool.