Add the fresh blueberries to a medium bowl and add 2 Tablespoons of flour. Toss to coat and set aside.
Measure out sifted flour and add to a large bowl with the baking powder and baking soda.
Add the sugar and salt to the same bowl and use a whisk to fully combine.
In a separate medium bowl, add the eggs, sour cream, vanilla, oil, melted butter and milk. Whisk until fully integrated and smooth.
Create a well in the center of the dry ingredients and pour the wet ingredients into the well.
Gently whisk JUST until the batter is fully combined. Be careful not to overmix. There will still be a few smaller lumps.
Add the blueberries (omitting any extra flour left in the bowl) and use a rubber spatula or wooden spoon to gently fold them into the batter.
Cover the bowl with plastic wrap and allow it to rest on the counter for 45 minutes.
Preheat the oven to 425 degrees and set a rack to the middle of the oven.
Line a regular baking tin with paper liners using every other well.
Use a cookie scoop or large spoon to fill the muffin liner all the way to the top, and then a smidge more in the center.
Divide the streusel topping between the muffins. Be generous with this topping as when the muffin rises the streusel topping will become more spaced.
Add an extra fresh berry to the top as well and sprinkle with Raw sugar.
Bake the muffins at 425 degrees for 7 minutes, and then without opening the oven door, decrease the temperature to 350 degrees and continue baking for another 12-14 minutes. You may need additional time to ensure they are baked through. Touch the top of the muffin, and if it feels jiggly, give it a few more minutes. The top should feel firm. (If you are baking 12 muffins you’ll need to bake at 425 for 5 minutes and then 350 for about 15 minutes.)
Remove the pan of muffins and allow them to cool for a few minutes before transferring the muffins to a cooling rack.