In a bowl, combine the flour, baking powder, baking soda and salt. Set aside.

In another bowl, mix together the brown sugar and white sugar. Add the oil and butter. Stir to mix well. Mix in the egg, then add in the sour cream and mix until combined.

Gently fold the wet ingredients into the dry ingredients, folding together gently just until mixed. Do not overmix.

In a small bowl, toss the frozen blueberries with the two tablespoons of flour until the blueberries are coated. Add the blueberries to the muffin batter, discarding the extra flour. Gently fold the blueberries into the muffin batter.

Spray a muffin pan with cooking spray. Spoon the batter into the prepared pan, dividing the batter between 12 cups.

Sprinkle the turbinado sugar on top of each muffin.

Bake at 425 for 5 minutes, then without opening the oven, lower the temperature to 350 and bake for 14-16 minutes.

Allow the muffins to cool for 10 minutes, then remove them to a wire rack to cool completely.