01 - Combine granulated sugar with 1 cup of water in a small saucepan. Heat gently while stirring until sugar dissolves completely. Remove from heat and allow syrup to cool slightly.
02 - In a large pitcher, combine freshly squeezed lemon juice and the cooled simple syrup.
03 - Pour in the remaining 3 cups of cold water and stir thoroughly to integrate all ingredients.
04 - Sample the mixture and adjust sweetness or tartness by adding more sugar or lemon juice as preferred.
05 - Refrigerate the mixture for at least 30 minutes to ensure it is well chilled.
06 - Serve the lemonade over ice cubes, garnished with lemon slices and fresh mint leaves if desired.