Prepare the gluten free low carb pie crust ahead of time and store in the fridge for up to 5 days beforehand. You can prepare up to 4 months in advance and store in the freezer.
In a large bowl, combine strawberries, blueberries and half the sweetener and toss to combine. Cover, and set aside for 45 minutes while you work on the pie crust.
Partially bake the gluten free pie crust bottom according to our recipe. Prepare the top crust by rolling the crust out between two pieces of parchment, as opposed to a lightly floured surface. Cut the crust into strips to help you make a lattice like shape later. Freeze the strips on a baking sheet for 15-20 minutes, or while you prepare the rest of the pie. After 45 minutes or so, using a metal sieve, strain away juice that has gathered at the bottom of the berries. You can save the sweet berry juice to make a refreshing drink. Add the remaining sweetener, lemon juice and zest, kosher salt and vanilla extract to the berries and combine well. Now, slowly add in the cornstarch and xanthan gum in batches to the berry mixture, and combine well. Spread the berries into the prepared pie crust.
Preheat oven to 350°F. Gently arrange your top crust or lattice like design on top of your pie. We simply made a design, as we find the strips tricky to work with since they are so delicate.Brush the dough strips with an egg wash made with one egg whisked with one tablespoon of cream or milk. Place small pieces of butter between the different sections of the crust.
Cover the pie edges with aluminum foil again and place the cast iron on a baking sheet to make it easier to get in and out of the oven, as well as catch any drips. Bake for 45-55 minutes watching closely. After the pie is finished baking, allow to cool for 3 hours or more before cutting in. After pie has cooled, serve with a scoop of low carb ice cream!
Store in the fridge for up to 5 days in an airtight container, or in the freezer for up to 3 weeks.