Bánh Khoai Môn Pie (Taro Pie)

RECIPE: Bánh Khoai Môn Pie (Taro Pie)
For Taro Filling
2 pounds of Taro roots
3 Eggs
1 1/2 cups Sugar
4 tablespoons All-Purpose Flour
2 cups Whole Milk
1 teaspoon Pure Vanilla Extract

For Pie Shells (make two 9-inch pie shells)
2 1/2 cups All-Purpose Flour
1/2 teaspoon Salt
3 tablespoons Sugar
1/4 cup Vegetable Shortening, cold
1 1/2 stick Unsalted Butter (12 tablespoons), cubed and cold
2/3 cup Iced Water
Making Pie Shells
Cut butter into cubes and keep butter cubes and vegetable shortening cold in the fridge.
In a large mixing bowl or a clean surface, mix flour, sugar and salt well. 
Add the shortening and break it up with your hands as you start to coat it up with the flour.
Add the cold butter cubes and work it into the flour with your hands quickly, so the butter doesn't get too soft, until the mixture is crumbly. 
Sprinkle in water, a little at a time and mix it with your hands until the mixture comes together forming a dough. Pack the dough together into a ball.
Divide the dough in half and flatten it slightly to form a disk shape.  Wrap each disk in plastic wrap and chill in the refrigerator for about 30 minutes before rolling out.
Unbaked pie dough can be kept in the refrigerator, tightly wrap with plastic wrap and foil, for about 4 days. Let it soften a bit at room temperature before you roll it out. It can also be frozen for at least 3 months. 
Making Taro Filling
Cut taro into big chunks.  In a pot, cover taro with just enough water and bring it to a boil.  Reduce heat and cook for about 15-20 minutes or until the taro is cooked.
Discard the water and place taro in the food processor and puree until a fine paste is formed.  Transfer taro into a mixing bowl. 
Beat eggs lightly  in a separate bowl.  Combine eggs and the remaining taro filling ingredients in taro mixing bowl.  Mix well and set aside.
Putting Taro Pie Together
Preheat to 350 degrees.
On a lightly floured surface, roll each disk out into an 11 or 12-inch circle, 1/8-inch-thick using a flour-dusted rolling pin; ultimately this is used to make a 9-inch pie. 
Roll the dough onto a rolling pin to facilitate transferring into a 9-inch pie pan.   Gently fit the pastry into the pan without stretching it; let it hang over the edge.  Add taro filling.
Roll up the overhang and pinch the edge with your thumbs and index fingers into a fluted rim. Brush egg yolk over the fluted rim. 
Baking Pie
Bake the pies for 30-40 minutes or until a toothpick inserted in the middle of the pie comes out dry.  Cool before slicing. 
Happy Baking!