Raspberry Shrub (Aka Drinking Vinegar)

Place raspberries, lemongrass, and vinegar into a non-reactive container that can be tightly sealed. (I don't wash the raspberries because they are so fragile, and I don't want to lose any of their juice. If you need to you may gently rinse them.)
Seal the container and allow to rest at room temperature for 3 to 5 days, stirring once to twice daily. The berries will basically disintegrate within a day or so.
Transfer vinegar and berries to a non-reactive saucepan. Stir in 1/2 cup sugar. Bring to a boil over med-high heat, then reduce heat to low. Simmer as gently as possible, uncovered for one hour, stirring on occasion. (Note: boiling vinegar is quite pungent, make sure you have good ventilation!)
Strain a tablespoon or two of the mixture into a glass, and allow it to cool. Add seltzer water, then taste. Add sugar if desired (I ended up adding another 1/4 cup of sugar.) Once it is the desired sweetness, remove from heat and allow to cool for 15 to 20 minutes. Strain the entire mixture through a mesh strainer set over a bowl, pressing as much of the liquid out of the fruit pulp as possible. Strain the collected liquid through a mesh strainer lined with several layers of cheesecloth into a quart-sized pitcher or glass measure. Transfer to a bottle, cool to room temperature, seal, and store in the fridge. Use as you see fit!
* Look for coconut vinegar at Asian groceries. It is a translucent white color, and has a mild flavor making it a perfect vehicle for your fruit to shine!