Preheat oven to 425°F (220°C) and line a 12-cup muffin tin with paper liners.
Whisk together flour, baking powder, baking soda, and salt in a large bowl.
In another bowl, combine melted butter and sugar, then add eggs one at a time. Stir in buttermilk, vanilla, and lemon zest.
Fold wet ingredients into dry ingredients until just combined. Toss blueberries with 1 tablespoon flour, then gently fold into batter.
Fill muffin cups almost to the top, sprinkle with cinnamon-sugar mixture, and bake at 425°F for 5 minutes.
Without opening the oven, reduce temperature to 350°F (175°C) and bake 15-18 minutes more until golden and a toothpick comes out clean.
Cool in pan for 5 minutes before transferring to a wire rack to cool completely.