Preheat the oven to 450 degrees.
In your pie plate, combine the flour, sugar, and salt for the crust. Mix together with a fork.
Add oil and milk and whisk until well combined. Press into the ungreased pie plate.
The pie crust mix will be wet. That’s okay.
In a medium bowl, combine the flour and sugar for the filling.
Sprinkle approximately ⅓ cup of the mixture onto the pie crust.
Mix rhubarb into the remaining flour and sugar and pour onto the unbaked pie crust that has been topped with the flour/sugar mixture.
Bake for 15 minutes at 450 degrees. Then drop the temperature to 350 degrees and bake an additional 30-40 minutes, until the rhubarb has set. It will set more after you pull it from the oven as well.