Preheat the oven to 375°F and line a 12-cup muffin pan with paper liners.
In a large bowl, whisk together flour, baking powder, and salt.
In another bowl, whisk the melted butter with sugar until smooth, then add eggs, vanilla, and sour cream.
Pour the wet ingredients into the dry mixture and gently fold until just combined.
Fold in the blueberries and lemon zest. Don’t overmix—lumpy batter is happy batter.
Divide the batter evenly among the muffin cups, filling about 3/4 full.
Bake for 20 to 25 minutes or until a toothpick inserted comes out clean.
Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.