A refreshing summer drink that can be made for the whole family or just the grown-ups.
Blend cherries in a blender at low speed until skins have broken down enough to brightly color liquid. Pour through a sieve into a 2-quart pitcher, pressing on and discarding solids. Add lemon juice and sugar (to taste), stirring until sugar is dissolved.
Pour 3 tablespoons vodka (if using) into each of 8 tall (10-ounce) glasses filled with ice. Add 1/2 cup cherry lemonade to each and top off with sparkling water.
Sour cherry lemonade can be made 1 day ahead and chilled, covered.