Preheat oven to 350°F.
Grease & line loaf pan with parchment paper.
Whisk flour, baking powder, and salt together.
Cream butter & sugar until light and fluffy.
Add eggs, sour cream, lemon juice, zest, and vanilla; mix well.
Gradually add dry mixture to wet in 3 parts, mixing gently.
Toss blueberries in 1 tablespoon flour, then gently fold into batter.
Bake 60–70 minutes, until toothpick inserted comes out clean.
Cool 15 minutes in pan, then transfer to wire rack.
Whisk glaze ingredients and pour over cooled bread.