To a saucepan add mint leaves, sugar, lemon zest, and water. Bring to a boil over medium heat, stirring until the sugar dissolves, and cook for 2 minutes. Remove from the heat, stir in vanilla, and set aside to cool. Strain liquid through a fine-mesh strainer and set aside.
In a large bowl, toss the berries and fruit together until combined. Pour ½ cup of the mint syrup over the fruit and gently toss. Serve immediately or chill for 30 minutes for the flavors to develop.
You can also serve in individual glasses topped with fresh mint sprigs for a fun presentation.