Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, using an electric mixer, cream the softened unsalted butter and granulated sugar together until light and fluffy, about 2-3 minutes.
Add the egg, vanilla extract, lemon zest, and lemon juice to the butter and sugar mixture. Beat until combined.
Mix in the sour cream until fully incorporated.
Gradually add the dry flour mixture to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Gently fold in the fresh blueberries with a spatula, being careful not to crush them.
Using a cookie scoop or spoon, drop about 2 tablespoons of dough per cookie onto the prepared baking sheets, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden and the tops are set.
Remove from the oven and allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.