3 cups fresh lemon juice (about 12 large lemons), strained
3 cups club soda or ice water
Mint sprigs, for serving
Prepare the simple syrup: Place the water and sugar in a medium saucepan and bring ro a boil over high heat, stirring with a wooden spoon until the sugar dissolves. Boil without stirring for 5 minutes. Cool to room temperature. Cover and refrigerate. (Refrigerated, the syrup will keep for 3 to 4 weeks.)
In a large pitcher, combine 1½ cups of the lemon juice with 1 cup simple syrup and 3 cups cold water. Mix and pour into ice-cube trays and freeze.
When ready to serve, combine the remaining 1½ cups lemon juice, 1 cup simple syrup and 3 cups soda water in a pitcher and mix. Pour over tall glasses filled with the lemonade ice cubes. Add a mint sprig to each and serve.
For other fruit flavors, such as strawberry, raspberry, pineapple, and watermelon, combine 1 cup strained pulp, 1 cup simple syrup, and 3 cups cold water. Freeze in the ice-cube tray. Use as ice cubes for the lemonade.