In a medium saucepan, combine the strawberries and sugar. Cook over medium heat for about 10 minutes, stirring occasionally, until the strawberries are soft and the sugar has dissolved.

Remove the saucepan from the heat and let the strawberry mixture cool slightly.

Transfer the strawberry mixture to a blender and blend until smooth.

Strain the blended strawberry mixture through a fine-mesh sieve into a large pitcher to remove any seeds.

Add the freshly squeezed lemon juice and cold water to the pitcher, and stir well to combine.

Taste the lemonade and adjust the sweetness or tartness by adding more sugar or lemon juice if needed.

Fill glasses with ice cubes and pour the strawberry lemonade over the ice.

Garnish with fresh mint leaves and lemon slices if desired, and serve immediately.