In a blender, combine the sliced peaches and 1 cup of cold water. Blend until smooth. Strain the mixture through a fine mesh sieve into a large pitcher to remove the pulp, pressing down to extract as much juice as possible.

Add the fresh lemon juice and sugar to the pitcher with the peach juice. Stir well until the sugar is completely dissolved.

Pour in the remaining 3 cups of cold water and mix until combined. Taste and adjust sweetness by adding more sugar if desired.

Chill the peach lemonade in the refrigerator for at least 1 hour before serving.

Serve over ice cubes and garnish with fresh mint leaves if desired.