Preheat the oven to 350°F (175°C).

In a mixing bowl, stir together 1 cup + 2 tablespoons flour, 1 tablespoon sugar, and 1/2 teaspoon salt. Add the oil and milk, and mix until the dough forms.

Press the crust mixture evenly into a 9-inch pie pan using your fingers or the back of a spoon.

Scatter the blueberries evenly over the crust and set aside.

In a separate bowl, whisk together 1 cup sugar, 1/3 cup flour, 1/8 teaspoon salt, eggs, and sour cream until smooth and combined.

Pour the custard mixture over the blueberries in the pie shell.

In another bowl, mix the remaining granulated sugar, brown sugar, and flour for the topping. Cut in the cold butter with a fork or pastry cutter until crumbly.

Sprinkle the crumb mixture evenly over the custard layer.

Bake the pie for 50–55 minutes, or until the center is set and the topping is golden brown. The internal temperature should reach 160°F (71°C).

Let the pie cool on a wire rack. Refrigerate before serving if cleaner slices are desired.