Preheat the oven to 325°F (163°C) and line a 9-inch loaf pan with parchment paper or grease it with cooking spray.

In a medium bowl, whisk together 1.75 cups of the flour, baking powder, salt, and lemon zest; set aside.

In a large bowl, beat the softened butter and granulated sugar on medium-high speed for 3 to 4 minutes until pale and fluffy.

Add the eggs one at a time, mixing for about 30 seconds after each addition.

Alternately add the flour mixture and sour cream to the butter mixture, beginning and ending with flour, mixing on low speed until just combined.

Stir in the vanilla extract and lemon juice until no streaks remain.

Toss the remaining 0.25 cup flour with the blueberries to coat; gently fold half the blueberries into the batter, then pour into the prepared pan and top with the remaining berries.

Bake for 50 to 60 minutes at 325°F (163°C) until the top is golden and a toothpick inserted in the center comes out with a few moist crumbs.

Let the cake cool in the pan for 10 minutes, then transfer to a cooling rack to cool completely before slicing.