Preheat the oven to 200°. Lightly oil 2 large racks and set them over 2 large baking sheets or line 2 large baking sheets with parchment paper. Set the tomato halves on the racks and bake for 2 hours, rotating the sheets for even drying. Reduce the oven temperature to 150° and bake for 3 hours longer, rotating the sheets, or until the tomatoes are dry and firm but still a bit moist. Transfer the tomatoes to a medium bowl while they are still warm. Let cool completely. Transfer the tomatoes to a sturdy plastic bag or an airtight container and freeze indefinitely; defrost before using
