Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners, or grease the pan using cooking spray.
In a large bowl, combine the flour, granulated sugar, baking powder, baking soda, and salt. Whisk them together until evenly mixed.
In a separate bowl, mix the melted butter, egg, sour cream, and vanilla extract. Whisk until smooth and creamy. Stir in the lemon zest for added flavor.
Pour the wet ingredients into the dry ingredients and gently fold with a spatula until just combined. Be careful not to overmix; it’s okay if a few lumps remain.
Gently fold in the fresh blueberries, making sure they are evenly distributed throughout the batter.
Scoop the batter into the prepared muffin tin, filling each cup about 3/4 full. Sprinkle a few extra blueberries on top of each muffin and then add a pinch of coarse sugar for a delightful topping.
Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean (or with a few moist crumbs).
Allow the muffins to cool in the pan for about 5 minutes, then transfer them to a wire rack to cool completely.
Notes
For best results, use fresh blueberries and do not overmix the batter.