01 - Combine sugar and 1 cup cold water in a small bowl or measuring cup and stir until sugar dissolves completely.
02 - Pour freshly squeezed lemon juice and prepared simple syrup into a large pitcher and stir to combine.
03 - Add remaining 3 cups cold water to the pitcher and stir well.
04 - Taste and adjust sweetness or tartness by adding more sugar or lemon juice as preferred.
05 - Add ice cubes, lemon slices, and mint leaves to the pitcher or individual glasses for garnish and serve chilled.