01 - Combine the granulated sugar and freshly squeezed lemon juice in a small pitcher or large bowl. Stir until the sugar has completely dissolved.
02 - Pour in the cold water and mix thoroughly. Taste the mixture and adjust sweetness or tartness by adding additional sugar or lemon juice as preferred.
03 - Fill serving glasses with ice cubes to chill the beverage.
04 - Pour the lemonade into the prepared glasses and garnish each with lemon slices and fresh mint leaves if desired. Serve immediately.