Whisk the flours, sugar and salt in a large bowl.

With your fingers, quickly rub butter into the dry ingredients until the pieces are smaller in size but still visible.

Add sour cream and oil and toss with a fork to combine.

Sprinkle water over the mixture and toss with a fork until evenly moist.

Knead the dough in the bowl a few times -- the mixture will still be a little crumbly.

Turn onto a lightly floured surface and knead a few more times, until the dough just holds together.

Shape into a circle approximately 5 inches around, wrap in plastic, and refrigerate for 1 hour.

Remove the dough from the refrigerator; let stand for 5 minutes to warm slightly.

Roll between sheets of parchment or wax paper into a 13-inch circle.

Peel off the top sheet and invert the dough into a 9-inch pie pan.

Peel off the remaining paper.

Trim the crust so it overhangs the edge of the pan evenly (you can use kitchen shears or a butter knife).

Tuck the overhanging crust under, forming a double-thick edge.

Using your fingers, flute the edge.

Proceed with your favourite pumpkin pie recipe.