Combine 1/3 cup sugar and 1 1/2 Tbsp. cornstarch in a small bowl. Combine berries, cornstarch mixture, and lemon rind in a large bowl until well blended; spoon berry mixture into a lightly greased 2-qt. baking dish.
Combine flour, cornmeal mix, and remaining 2/3 cup sugar in a medium bowl. Stir in butter and milk until blended. Gently spread batter evenly over berry mixture.
Bake at 350° for 40 to 45 minutes or until a wooden pick inserted in center of topping comes out clean. Serve warm.