1. Toss peaches with sugar, tapioca starch, and lemon juice. Filling can be made ahead of time and frozen in a zip-top freezer bag.
2. To assemble pie, preheat oven to 375 degrees and transfer peach mixture to a prepared crust (thawing first, if filling is frozen). Top with second crust and bake until crust is golden brown and filling is bubbling, about 1 hour.