To make this recipe gluten free, replace the all-purpose flour in the pastry with a high-quality 1:1 gluten-free baking flour blend that contains xanthan gum or another binding ingredient. Also confirm that the corn syrup, vanilla extract, vinegar, and any optional add-ins such as raisins or pecans are certified gluten free, as ingredient sourcing and processing can vary by brand. Because gluten-free pastry can be more delicate, chill the dough thoroughly before rolling and handle the tart shells gently when pressing them into the muffin pan.