In a medium saucepan, combine sliced fresh strawberries, granulated sugar, and water over medium heat. Cook for about 30 minutes, then strain into a bowl and set aside to cool.

Bring 2 cups of water to a boil in another saucepan. Remove from heat, add the black tea bags, and let steep for 5 minutes. Remove the tea bags and stir in remaining sugar.

In a large pitcher, mix strawberry syrup with brewed tea and 2 cups of cold water. Add fresh lemon juice and stir until combined.

Fill glasses with ice cubes and pour the tea mixture over the ice. Garnish with fresh mint leaves or sliced strawberries if desired.