Preheat oven to 450°F Coat a large baking sheet with cooking spray; set aside.
In a large bowl combine flour, cornmeal, granulated sugar, brown sugar, baking powder, baking soda, and 1/2 teaspoon salt. Cut in butter until flour mixture resembles coarse crumbs. Make a well in center.
Combine buttermilk, egg, and peel; add all at once to flour mixture. Stir with a fork just until moistened.
Toss berries with cornstarch to coat; add to flour mixture. Stir gently 3 to 5 turns, just until berries are incorporated (do not overmix). Using a large spoon, drop dough into 12 mounds on baking sheet, leaving 1 inch between mounds.
Bake 12 to 15 minutes or until tops are golden. For icing, in a small bowl whisk enough lime juice into powdered sugar until drizzling consistency. Drizzle over warm scones. Sprinkle with nuts. Serve warm. Makes 12 scones.
*Leave berries in the freezer until ready to toss with cornstarch.