In a small saucepan, combine the sugar and 2 cups water. Heat over medium heat, stirring, just until the sugar fully dissolves. Remove from heat and let cool completely.
Add the strawberries and chopped peaches to a blender and blend until completely smooth.
For a smoother lemonade, strain the puree through a fine mesh sieve to remove the solids. Skip this step if you prefer a more textured, pulpy lemonade.
In a large pitcher, combine the fresh lemon juice, cooled simple syrup, and fruit puree. Stir well.
Add 2 to 2 1/2 cups of cold water and stir. Taste and adjust the sweetness or water level to your preference.
Chill well and serve over ice with peach slices, strawberry slices, lemon wheels, and fresh mint as garnish.
