In a large bowl, sift together the flour, baking powder, salt, and sugar.
In a separate medium bowl, whisk the buttermilk, egg, melted butter, and vanilla until smooth.
Pour the wet mixture into the dry ingredients and stir gently just until combined. A few small lumps are fine. If the batter seems too thick to pour, add 1 to 2 tablespoons more buttermilk.