1. In medium bowl, whisk together flour and salt. Add butter and mix into flour with a pastry blender or your fingers until crumbly. In a small bowl, stir together maple syrup and 1/4 cup plus 1 teaspoon cold water. Add water mixture to flour mixture and toss together with a fork until dough begins to come together. Gather dough into a ball; divide in 4 equal pieces. Flatten each into a disc, wrap in plastic and refrigerate 2 hours.Blueberry Filling:
2. Heat oven to 375 degrees F. Place blueberries in a large bowl. In small bowl, stir together maple syrup, cornstarch and lemon zest. Gently combine with blueberries. Set aside.
3. Roll out one pastry disc to an 8-inch circle. Transfer to a nonstick baking sheet. Fold over 1/2 inch of dough all around pastry, forming a decorative edge. Repeat with remaining pastry. Divide blueberry mixture evenly among pastry rounds, about 1/2 cup in each (spread berry mixture in single layer).
4. Bake tarts at 375 degrees F for 35 minutes, until pastry is browned and filling is set.