This recipe comes from the fabulous Moosewood New Classics cookbook and is a perfect summer treat. The recipe says that the strawberry puree can be kept for up to four days in the refrigerator.I don't actually know--it's never lasted that long.
3 large lemons usually makes at least a cup of juice. Zap the lemons for 1 minute in the microwave to make them as juicy as possible before squeezing.
In a small saucepan over medium heat combine sugar and water. Stir until sugar is completely dissolved and the liquid is clear.
Pour the sugar syrup into a blender with the strawberries and lemon juice and puree.
If serving immediately combine the puree and sparkling water in a pitcher and serve in tall glasses over ice. Or refrigerate the puree and prepare individual servings by mixing equal parts puree and sparkling water.