This pineapple ginger agua fresca is a refreshing drink for any time of year. You can make it into a spritzer by only using 1/2 cup of water when blending the agua fresca in the blender, then stirring in sparkling water before serving.
Mix the water, sugar, and ginger in a small, heavy saucepan and bring to a boil over medium heat. Once the syrup comes to a boil, reduce the heat to maintain a steady simmer and continue cooking for an additional 25 minutes.
Remove the saucepan from the heat and stir in the finely grated lime zest. Let the syrup cool to room temperature, then strain the syrup through a fine mesh sieve. Pour the syrup into an air-tight container and put in the refrigerator to chill.
Combine the water, frozen pineapple, ginger syrup, and lime juice in a blender. Puree until smooth. Pour the agua fresca into glasses, garnish with a pineapple wedge (optional), and serve immediately.