In the bowl of a food processor, combine flour and salt by pulsing 3 to 4 times. Add butter and pulse 5 to 6 times until texture looks mealy. Add lard and pulse another 3 to 4 times. Remove lid of food processor and spritz surface of mixture thoroughly with water. Replace lid and pulse 5 times. Add more water and pulse again until mixture holds together when squeezed. Place mixture in large resealable bag, squeeze together until it forms a ball, and then press into a rounded disk and refrigerate for 30 minutes.
Preheat oven to 425 degrees F.
Place 2 (9-inch) metal pie pans in the refrigerator to chill.
Remove dough from refrigerator and roll out in the bag until it reaches the edges of the bag and is 10 to 11-inches round. Cut along 2 sides of the plastic bag, open bag to expose dough on 1 side and turn a 9-inch pie pan upside down on the exposed side. Invert the entire thing and gently pull the remaining side of the plastic bag off the dough. Press the dough into the edges around the pan and trim any excess dough. Press the edges of the dough over the lip of the pan. Place in refrigerator for 15 minutes.
Poke holes around sides and into the bottom of the dough. Place a large piece of parchment paper on top of dough and fill with dry beans. Press beans into edges of dough, set on a baking sheet, and bake in the oven for 10 minutes. Remove parchment and beans and continue baking until light golden in color, approximately 7 minutes longer. Remove from oven and place on cooling rack. Allow to cool completely while preparing the filling.
Decrease heat of oven to 350 degrees F.
Place the flour, brown sugar, butter and salt into the bowl of a food processor and process until it forms crumbs. Reserve 1/4 cup and set both aside.
Place the baking soda in a medium mixing bowl and pour the boiling water over it. Add the molasses, egg, and vanilla; whisk to combine. Add the larger amount of crumbs to the molasses mixture and whisk just to combine. Pour this mixture into the prepared crust. Sprinkle the remaining 1/4 cup of crumb mixture evenly over the top of the filling. Place pie on the middle rack of the oven and bake for 40 to 45 minutes or until the filling puffs, begins to look dry and starts to crack slightly. Remove from the oven, transfer to a rack, and cool completely before cutting.
Recipe courtesy of Alton Brown, 2009