Preheat oven to 425°F.

In a large bowl, add flour, salt and fat. Using two butter knifes or a pastry cutter, cut the fat into the flour until it forms a dry small crumble mixture.

Add COLD water. Using knifes or pastry cutter blend until a dough forms. Set aside or place in fridge until ready to roll out.

In a large bowl, add rhubarb pieces, strawberry halves, sugar, cornstarch, salt and tapioca. Toss and stir until coated.

Split pie dough into two equal pieces. On a well-floured surface roll out to 1/8 inch thick. Dough needs to be about 3 inches larger than pie dish (8 or 9 inch DEEP pie dish. *see notes).

Carefully press one half rolled out pie dough into pie dish. Remove any excess by cutting with a knife.

Add strawberry rhubarb filling.

To make the lattice, cut second rolled out pie dough into long 1-inch wide strips. Place long strips in a weaving pattern (lattice) on top of filling. Cut excess dough from edge.

Crimp edge using fingers or a fork.

Brush lattice pie dough with egg wash.

Place a small piece of butter in each lattice hole.

Sprinkle with cinnamon sugar.

Bake at 425°F for 20 minutes then reduce temperature to 350°F for an additional 50-60 minutes or until crust is consistently golden brown and pie is cooked through.

Let pie cool before slicing (1-2 hours). Serve warm, room temperature or a la mode.