Preheat oven to 325° Fahrenheit. Generously grease a 12" tube pan.
In a medium bowl, mix together flour, salt, baking soda & lemon zest & set aside.
Using hand or stand mixer, cream butter and sugar until light and fluffy. Add eggs one at a time. Incorporating after each addition.
Add 1/2 of the flour mixture to the sugar & butter. Mix just until combined. Add 1/2 of the sour cream, mixing just until combined. Repeat with flour and sour cream.
Add lemon juice & extract, mixing until just combined. Toss still damp, washed blueberries in 1 Tbsp of flour. Fold gently into the cake batter. Pour into tube pan.
Bake in preheated oven for 1 hour 15 minutes or until toothpick comes out clean. Remove from oven. Run knife around inside and outside of the cake. Let cool for 10 minutes. Turn out onto cooling rack to finish cooling.
Mix confectioner's sugar, milk and lemon juice together. Drizzle over cake and let run down the sides. Sprinkle top with zest of 1/2 lemon. Slice and serve.
Freezing Instructions. Cake can be covered tightly before glazing and frozen for 2-3 months. Let thaw, glaze and serve.