Preheat oven to 350°F and lightly grease a loaf pan or line with parchment paper
In a large bowl, mix together buttermilk, oil, egg, vanilla, lemon zest and lemon juice.
Add flour, sugar, baking powder and salt and mix to just combine
Gently fold in blueberries
Pour into prepared pan
Bake for 45-50 minutes, or until a toothpick inserted in center comes out clean
Cool in pan 5 minutes before transferring to a cooling rack.
Slice and serve