Preheat the oven to 350F, and line a muffin pan with liners.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In the bowl of a stand mixer, beat together the butter, oil, and sugar until light and fluffy.

Add in the eggs, one at a time, beating until combined.

Add in the sour cream and vanilla, followed by the flour mixture. Mix until just combined, and don't over-beat! Finally, gently fold in the blueberries.

Divide the batter among the prepared muffin liners, and top each muffin with a couple more blueberries and a spoonful of turbinado sugar.

Bake for 25-30 minutes, until muffins are golden brown and puffy, and a toothpick inserted in the center comes out clean.