To make mint simple syrup, add mint leaves, sugar and water to a large measuring bowl and microwave for 2-3 minutes. Remove from microwave. Use a wooden spoon to stir until sugar is dissolved. While stirring, gently press the mint leaves against the side of the bowl 2-3 times to release the essential oil into the syrup. Leave mint in bowl and set aside to cool.
In a 2 quart pitcher, add fresh squeezed lemon juice, ice and cold water. Strain mint leaves from the simple syrup and add syrup to the lemon water. Stir well. Taste. Add additional lemon juice, if desired.
Add 3-4 lemon slices and 1-2 extra sprigs of mint to pitcher of mint lemonade. Place in refrigerator to chill for at least 30 minutes before serving.