In large bowl, mix flour, 1/3 cup sugar, the baking powder, salt and baking soda. Grate butter into flour mixture, then work in with fingers until mixture looks like coarse meal. In small bowl, beat sour cream, egg and lemon peel with whisk or fork. Add sour cream mixture and blackberries to flour mixture. Stir until dough comes together (some berries may become slightly crushed).