Combine one 12-ounce can thawed frozen pink lemonade concentrate, 1/2 cup water and 12 torn basil leaves in a medium skillet; cook over medium-high heat until syrupy, about 10 minutes. Stir in 8 more torn basil leaves; let cool, then strain. Add seltzer.
For each drink, combine 2 to 4 tablespoons flavored syrup with 1 cup cold seltzer in an ice-filled glass.
Photograph by Charles Masters