Line a loaf pan with parchment paper and butter or coat with nonstick baking spray and lightly dust with flour.
In a small bowl add the blueberries and gently coat with the 1 tsp flour. Set aside.
In a medium bowl, combine the flour, baking powder, salt. Set aside.
Separate egg whites from egg yolks. Place egg whites in one bowl and egg yolks in another.
On high speed, with a mixer, beat egg whites until soft peaks form. Slowly add sugar, continue beating until stiff peaks form.
Add sour cream, lemon zest, lemon juice and oil to the egg yolks. Beat until well incorporated and the mixture gains some volume, about 2 minutes. (You can use the same whisks as you did for the egg whites, no need to wash them).
Pour egg yolk mixture in egg whites/sugar. On low-speed beat just until everything is combined.
Add flour mixture in two parts. Add half the flour beat on low-speed, add remaining flour and beat again until well combined.
Pour 2/3 of the mixture into your pan. Add 1/3 of the blueberries. Pour remaining mixture and spread evenly. Add remaining blueberries.
Bake 40-55 minutes. Check center of loaf with a toothpick. If it comes out clean, the cake it ready.
Once loaf cools a bit, remove from pan and set on a baking rack to completely cool.
Beat all the ingredients for the glaze. Either spread glaze over the entire loaf or place in drizzle over the loaf.
Enjoy, friends.
Notes
Once the loaf is completely cooled. You can just dust it with powdered sugar and enjoy. Or you can make the glaze and either spread it over the loaf or drizzle it.