To make the pie crust: Have all of your ingredients ready and chilled. Combine the flour, salt and sugar.
Add the butter. Use a pastry cutter or your hands to work the butter into the flour, until it looks like cornmeal and starts to stick together when squeezed. You want to keep some of the butter in pea-sized pieces. If the butter is too soft and it won't stay in pieces, place the bowl in the freezer for about 15 minutes and then try again.Add the shortening or lard in the same way, making sure to keep everything well chilled.
Mix together the water and vodka and add to the flour/butter mixture.
Stir this with your hand or a wooden spoon, but be very gentle. The goal is to keep the pea-sized chunks of butter in tact.
When most of the flour is coming together, gently fold the dough with a bench scraper into a ball. It should not be perfectly smooth, but, it should also not seem dry or crumbly. If there is still any powdery flour, you can add drops of water to the pie dough. Elongate the ball into a squat log.
Divide the dough into two pieces and create round disks. Wrap the dough in plastic and refrigerate for at least an hour, or overnight.
To roll out the pie crust:When you are ready to prepare the pie, roll one of the disks out on a floured surface. If the dough seems hard, let it sit at room temperature for about 10 to 15 minutes. This will prevent the edges from cracking too much. You still want the dough to be chilled, so the butter doesn't get too soft.
As you are rolling, you can round out the edges with your hands. Cracking edges are part of the beast, but this will help to keep them smoother.
Once you have it rolled out to about 1/8-inch thick round, measure the dough to make sure it will fit the 12-inch pie plate. I usually just hold the plate over the dough and eye it. There should be about 2-inches of extra dough beyond the bottom of the plate.
Fold the dough over the rolling-pin to lift it. Lift it over the plate and gently fit the crust into the plate. Do NOT trim the edges yet. Set the crust in the refrigerator while you prepare the filling.
To make the filling:Cook the strawberries and vanilla over gentle heat (use a fork to break up the fruit if using fresh strawberries) until they start to break down slightly. Cook until the strawberries are tender and have released their juices. Whisk together the sugar and cornstarch, then add the rhubarb and sugar mixture to the strawberries. Cook over medium-low heat until the mixture starts to thicken and turn translucent. Remove from heat and allow to cool to room temperature before filling the pie shell and covering with lattice top.This step can be done ahead and chilled, but it may increase the baking time by a little bit. To bake:Preheat oven to 425°F. It is best, but not a must, if you have a Pizza Stone or Baking Steel in the oven, to make sure you get a nice bottom crust.
Freeze the pie until the crust is quite hard before brushing with egg wash and sprinkling with sugar. Set the pie on a baking sheet (in case the juices bubble over) and then set it directly on the preheated baking stone/steel.
Bake for 30 minutes and then drop the temperature to 375°F. Continue to bake until the fruit juices are bubbling throughout the pie and it has puffed slightly in the middle. This can take up to an hour, depending on how long you froze the pie. If the edge of the crust is browning too quickly, tent with foil.
Allow the pie to cool completely before cutting or it may be too loose to cut. This pie will still have some juice to it and not set up solid, because I don't like a gloopy filling.If you want a cleaner slice, you'll want to add another tablespoon or two of cornstarch.