Preheat the oven to 375F degrees. Line a 12-cavity muffin pan with papers.
In a large bowl whisk together the flour, baking powder, baking soda & salt.
In a separate large bowl beat together the butter, sugar, and lemon zest until fluffy (about 2-3 minutes).
Beat the eggs into the butter mixture 1 at a time. Then stir in the vanilla extract and lemon juice.
With the mixer on low speed, beat in about ½ of the sour cream into the butter mixture. Then mix in about ½ of the flour mixture into the butter and sour cream mixture. Beat in the rest of the sour cream. Then turn the mixer off and carefully fold in the rest of the flour using a rubber spatula or wooden spoon. ***
If using frozen berries, in a separate bowl toss the berries with 2 teaspoons of flour.
Gently fold the berries into the muffin batter using a rubber spatula.
Spoon the batter into the prepared muffin pan, filling each muffin to the top. You'll end up with 12-14 muffins total.
Bake in the preheated oven for 17-20 minutes, or until the tops are golden and an inserted toothpick comes out clean or with blueberry juice (not muffin batter).
Cool in the pan for 10 minutes, then transfer to a wire rack and continue cooling.