Preheat the oven to 375 degrees Fahrenheit and line a 12-cup muffin tin with paper liners or grease each cup with butter.

In a large mixing bowl, whisk together the all-purpose flour, baking powder, and salt until evenly combined.

In a medium bowl, beat the softened butter and granulated sugar with a whisk until light and fluffy, about 2 minutes.

Beat in the eggs one at a time, mixing well after each addition, then stir in the vanilla extract and lemon zest.

Add the sour cream to the wet mixture and stir until just combined, being careful not to overmix.

Pour the wet ingredients into the bowl with the dry ingredients and fold together with a rubber spatula until just barely combined.

Gently fold the blueberries into the batter, using as few strokes as possible to keep the berries intact.

Divide the batter evenly among the prepared muffin cups, filling each nearly to the top.

Sprinkle 1/2 teaspoon of sugar over each muffin and bake for 25 to 30 minutes, or until the tops are golden and a toothpick inserted into the center comes out with moist crumbs.

Let the muffins rest in the tin for 5 minutes, then transfer to a wire rack to cool completely before serving.