Preheat your oven to 350F (175C). Grease a 9x5 inch loaf pan and line it with parchment paper, leaving an overhang on the long sides for easy removal.
In a medium bowl, whisk together the flour, baking powder, and salt. Toss the blueberries with 1 tablespoon of the flour mixture in a separate small bowl. This helps prevent them from sinking to the bottom during baking.
In a large bowl, beat the softened butter and granulated sugar with an electric mixer until pale and fluffy, about 3 minutes. Add the eggs one at a time, beating well after each. Mix in the sour cream, lemon juice, lemon zest, and vanilla extract.
Add the flour mixture to the wet ingredients and stir with a spatula until just combined. Gently fold in the coated blueberries. Pour the batter into the prepared loaf pan and smooth the top.
Bake for 50 to 60 minutes, until the top is golden and a toothpick inserted in the center comes out clean. If the top browns too quickly, tent it loosely with aluminum foil for the last 15 minutes.
Let the cake cool in the pan for 15 minutes, then lift it out using the parchment overhang and transfer to a wire rack to cool completely.
Whisk together the powdered sugar, lemon juice, and lemon zest until smooth. Drizzle the glaze generously over the cooled loaf. Let the glaze set for 10 minutes before slicing.