For the crust:
2 cups flour (260 g)
1 teaspoon salt
1 cup unsalted butter (2 sticks), cut into small cubes
1/2 cup full-fat sour cream
Whisk together flour and salt. Using hands, work the butter into the flour mixture. Add sour cream and work in with a fork. Once it starts to clump, knead with hands until the dough comes together. Divide in two, form disks, wrap in plastic wrap and chill for at least an hour.
For the filling:
6 cups rhubarb, small dice
1 1/3 cups sugar (290 g)
6 Tablespoons flour (54 g)
pinch kosher salt
1 Tablespoon butter
Preheat oven to 450 F.
Whisk together sugar and flour and salt. Sprinkle 1/4 of it over pastry in pie plate. Heap rhubarb over this mixture. Sprinkle with remaining sugar/flour/salt mixture. Dot with small pieces of butter. Cover with top crust. Crimp edges. (Optional: brush with egg/milk wash)
Place pie on lowest rack in oven. Bake for 15 minutes. Cover loosely with foil. Reduce oven temperature to 350 F, and continue baking for 40 to 45 minutes.
Serve warm or cold.
There is usually enough leftover pie crust for 2-3 hand pies:
Make mixture of 1/3 cup sugar and 2 Tablespoons of flour with tiny pinch of kosher salt. Save the leftover mixture for future use. Roll out pie crust and cut into about 6" diameter circles. Sprinkle 1/2 T of the sugar/flour mixture on the dough. Add 1/4 cup chopped rhubarb. Cover with another 1/2 T of the sugar/flour mixture. Add a dot of butter. Fold over and use water to seal the edges. Use water and fold the edges again. Use a fork to press into the edges pulling toward the pie. Brush with egg/milk wash. Bake for 15 minutes at 450, then cover with foil and then continue baking at 350 for another 15 minutes.
You can air fry two hand pies at 350 for 10 minutes in pre-heated fryer. Butter the surface first.