Preheat oven to 350°F. Line a 9x5-inch loaf pan with parchment paper and/or coat with nonstick spray.
In a large bowl, whisk together flour, sugar, baking powder, baking soda, salt, and lemon zest. Set aside.
In another bowl, whisk together lemon juice, buttermilk, oil, eggs, and vanilla. Pour into the dry ingredients and mix just until no dry bits remain.
Toss the blueberries with 1 tablespoon of flour to lightly coat, then fold berries into batter. Pour batter into prepared loaf pan.
Bake for 60-70 minutes, until a tester inserted into the center comes out clean. Let cool in the pan for 10 minutes, then remove to a wire rack to cool completely.
Notes
1 lemon will yield approximately 2-3 tablespoons juice. Use less or omit juice if you prefer a less tart flavor.