For cake:

Preheat oven to 350 degrees F. Grease and flour a 10-inch tube pan. Cream butter and sugar in large mixing bowl until light and fluffy. Add eggs, one at a time, beating well after each addition. Add the vanilla extract and lemon juice. Beat very well.

Combine the flour, baking soda, baking powder and salt in a separate bowl. Alternately add the dry ingredients and the sour cream into the butter mixture. *Begin and end with the dry

ingredients. Mix well. Gently fold in the blueberries.

For Streusel:

Combine sugars, flour and cinnamon in a bowl. Cut in chilled butter with a pastry blender until mixture resembles coarse crumbs. You can also use an electric mixer with a paddle attachment. *You will have some extra streusel--keep in freezer for quick fruit tart another day!*

Assemble and Bake:

Spread half of the batter into the prepared pan. Sprinkle with a layer of the streusel. Top with remaining batter, then top with another layer of streusel. Bake for approximately 55 minutes. Cake will be done when golden brown, sides of cake pull away slightly from edge of pan and toothpick inserted in center comes out clean. Remove pan from oven and cool on a rack for 45 minutes. Unmold onto rack streusel side down and allow to cool completely. Then invert, streusel side up onto a cake plate. Serve dusted with confectioners sugar or with blueberry sauce.

Sauce:

In a saucepan over medium low heat add blueberries, sugar mixed with cornstarch, vanilla bean seeds and lemon juice. Heat to a boil, stirring occasionally. Cool completely. Serve with cake, over ice cream.