In medium bowl, whisk together 2 1/2 cups flour, baking powder and salt.
In mixer bowl, beat butter, sugar and brown sugar. Add eggs, one at a time. Beat in vanilla. Reduce speed to low and add flour batches in 3 batches alternating with sour cream and ending with flour.
In a small bowl, add 1 Tsp flour and 2 Tbsp lemon zest. Add the blueberries and carefully mix to coat.
Gently fold the coated blueberries and remainder of zest mixture into the batter.
Transfer batter into prepared pan. Smooth the top of the batter. Bake 60-70 minutes until cake tester comes out clean. Cool in pan for 20-30 minutes before turning out onto rack. Dust the top with powdered sugar.