For a classic summer cocktail you can't beat the citrus and mint=Mojito.
15 fresh mint leaves, torn, and a sprig for garnish
2 Tablespoons fresh lime juice, plus slice for garnish
1 Tablespoon Agave (or simple syrup or sugar)
3 Tablespoons white rum
2 Tablespoons+ S.Pellegrino or club soda
In a tall, chilled glass combine the mint, lime and agave and muddle until oil from the mint is released and if using sugar, it is incorporated.
Fill the glass half full with crushed ice and add the rum. Stir. Add more ice and Pellegrino. Garnish with slice of lime and sprig of fresh mint.