Preheat the oven to 180C/375F degrees.
Add the ground chia, lemon juice and remaining sweetener to the two bowls of berries. Stir well.
Lightly butter an 8 inch pie dish.
Remove the pastry from the fridge and cut into half.
Place one half of the pastry dough on a sheet of parchment paper and cover it with another layer of parchment paper.
Roll out gently into a circle slightly larger than the pie dish.
Remove the top layer of parchment paper, then using a hand under the bottom parchment paper place the pastry into the pie dish.
Spoon the filling into the pie dish. First spoon the blueberries in the top left hand quarter of the pie. Fill the remaining pie with the strawberry mixture.
Take the second half of the dough roll out. Using a star cookie cutter, cut a few star shapes out. My cutter was medium size and I cut out 3 stars. Place the stars over the blueberry filling in the pie.
Cut strips from the remaining rolled pastry and place the over the strawberry filling in the pie.
Brush the pastry strips and stars with the egg wash.
Bake for 35 minutes until the top of the pie is lightly golden and firm.
Serve with cream or low carb vanilla ice cream.