Whisk together the oat flour, teff flour, and sugar in a bowl. Add in the coconut oil and use a pastry cutter to cut the oil into the flour until the oil is broken down into pea sized pieces. Add in the vanilla vodka and 2 tablespoons of the water and stir to combine, working with your hands if necessary to form a dough.
Add in up to 3 more tablespoons of water, one tablespoon at a time, until the dough has come together, but is not sticky. Form into a flat disk and wrap in plastic wrap. Place in the refrigerator to chill overnight or for at least 1 hour.
While the dough is chilling, preheat the oven to 350 degrees. In a small bowl, whisk together the remaining oat flour, sugar, cinnamon, and salt for the crumb. Add in the coconut oil, and use your fingers to pinch the oil into the flour and sugar. You want the oil to be evenly incorporated and the mixture to hold together when pinched. Set aside.
In another large bowl, toss together all of the filling ingredients. Store in the fridge until the crust is ready.
After 1 hour, remove the crust from the fridge. Place one piece of parchment paper down on the counter. Unwrap the crust and set it on the parchment. Cover with another piece of parchment and roll out the crust between the two layers until it will fit in a 9-inch pie pan. Remove the top parchment and slide the dough and bottom layer of parchment onto a cutting board.
Invert the pie dish on top of the dough. Grab the cutting board and pie dish and flip it over so that the pie dish is on the bottom, the cutting board is on the top, and the crust is sandwiched in between. Remove the cutting board and parchment.
Nestle the crust down into the pie dish and use your fingers to crimp the edges. Fill with the apple mixture. Evenly sprinkle the crumb topping over the pie and bake for 50-60 minutes. Allow to cool for 15-20 minutes and serve.