01 - Preheat oven to 350°F. Lightly grease a 12-cup mini muffin tin or tartlet pan with oil or cooking spray.
02 - In a medium bowl, whisk together flour, sugar, and salt. Add solid coconut oil and use a pastry cutter or fork to blend until mixture resembles coarse crumbs. Add cold water 1 tablespoon at a time, mixing until a cohesive dough forms.
03 - Divide dough into 12 equal portions. Press each portion into the bottom and up the sides of each muffin cup to form mini tart shells, ensuring even thickness.
04 - Prick the bottom of each tart shell with a fork. Bake for 10-12 minutes until lightly golden. Remove from oven and let cool completely in the pan.
05 - In a medium saucepan, whisk together lemon juice, lemon zest, coconut milk, sugar, cornstarch, turmeric (if using), salt, and vanilla extract until smooth and no lumps remain.
06 - Place saucepan over medium heat and whisk constantly until mixture thickens and just begins to bubble, about 4-6 minutes. Remove from heat immediately.
07 - Pour warm lemon filling evenly into cooled tart shells. Smooth tops with the back of a spoon or small offset spatula.
08 - Refrigerate tarts for at least 1 hour until filling is completely set. For best results, chill 2-3 hours before serving.
09 - Top with extra lemon zest or fresh berries if desired. Serve chilled. Store leftovers in the refrigerator for up to 3 days.