Combine water, sugar and half of the mint leaves in a small saucepan. Bring to a boil, stirring until sugar dissolves. Simmer for 1 minute.

Remove from heat and let syrup steep, about 30 minutes. Discard the mint leaves and refrigerate the syrup to let it cool.

Combine the mint simple syrup, the rest of the fresh mint leaves and the fresh lemon juice in a blender. Blend at high speed until well mixed.

Add the ice and blend until the ice is thoroughly crushed. Pour into glasses and serve immediately.