Make the Crust:

1. In a food processor, place the flour, sugar and salt.  Pulse to combine.  Add the COLD cubed butter. Pulse until the largest bits of butter are the size of a pea – you want to SEE the butter bits in the rolled out crust, this will make it flaky.  This took about 8-10 pulses in my processor.  Slowly add the water and stop when the dough just begins to form.  You will still have an amount of crumbly mixture but as long as it sticks together when you pinch it in your fingers, you’re good to go.
2. Pull out 2 separate 12″ sections of plastic wrap, and pour half of the dough mixture on each.  Shape each portion into a 4-5″ disk about 1″ thick and wrap tightly.  Refrigerate at least 1 hour and up to 24 hours.
3. Roll out the first portion of dough into a circle large enough to fill your pie plate. Place into the pie plate, filling in any areas that crack or separate with small pieces of dough – I know Martha’s don’t do this, but mine always do. Make sure there is enough edge to create a crimp or design around the edge if you wish.
4. Roll out the second portion into a 10″ circle.  Run a knife down the middle to separate the two halves.  Using a star-shaped cookie cutter, make several stars for the blue half of the pie.
5. Create 1″ wide “stripes” for the red half of the pie.  Refrigerate the pie crust while you prepare the fruit.

Prepare the Fruit:

1. Preheat oven to 400F.
2. Using 2 medium-sized bowls, place the blueberries (or blackberries) in one, and your red berries in the other.  Pour half of the sugar over the blue berries and half over the red berries.  Likewise, pour half of the cornstarch, lemon juice and lemon zest into each of the two bowls.  Mix berries with a silicon or rubber spatula
3. Pour the blue berries into one half of the pie, the red berries into the other half.
4. Top the blue berries with you cut-out crust “stars” and the red berries with some of your “stripes.”  (Extra Stars and Stripes you can bake separately for 15 minutes or roll out into “hand pies, that you can fill with jam or extra berries!)
5. Whisk together the egg and milk to make an egg wash.  Gently brush over the pie crust edge and Stars and Stripes.
6. Bake pie for 45-55 minutes in preheated oven until the filling is bubbly throughout.  If the crust browns too much during baking, cover brown areas with strips of aluminum foil to slow this process down.
7. Cool pie at least 45 minutes before serving.