Preheat oven to 350°.
Lightly spoon 1 cup flour into a dry measuring cup; level with a knife. Combine 1 cup flour and the next 4 ingredients (1 cup flour through baking soda), stirring well with a whisk. Place the granulated sugar and butter in a large bowl, and beat with a mixer at medium speed until well blended (about 2 minutes). Add egg and lemon rind; beat until well blended. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with the flour mixture. Toss blueberries with 1 tablespoon flour, and fold into batter.
Spoon the batter into 24 miniature muffin cups coated with cooking spray. Bake at 350° for 14 minutes or until the cakes spring back when touched lightly in center. Combine powdered sugar and juice, and drizzle over warm cakes.