Preheat the oven to 400°F. Line a 12-cup muffin pan with liners.
Whisk flour, sugar, baking powder, baking soda, salt, and lemon zest in a large bowl.
In another bowl, whisk buttermilk, beaten egg, vanilla, and melted butter until smooth.
Make a well in the dry ingredients and pour in the wet mixture.
Stir gently just until combined; a few dry streaks are fine.
Fold in raspberries carefully to avoid breaking them.
Divide batter among cups, about three-quarters full. Sprinkle with turbinado sugar.
Bake 16 to 18 minutes until golden and a tester comes out clean.
Cool 5 minutes in the pan, then move to a rack. Serve warm.