- Preheat oven to 400°F.
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Whisk 2 cups flour, 1/3 cup sugar, baking powder, baking soda, and salt in large bowl. 
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Add butter and grated orange peel; rub in with fingertips until coarse meal forms.  Mix in berries. 
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Whisk buttermilk, egg yolk, and vanilla extract in small bowl to blend. 
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Add buttermilk mixture to dry ingredients; stir with fork until dough comes together in moist clumps. 
- Drop dollops of the mixture onto baking sheet, spacing 1 inch apart. DO AHEAD Can be made 1 day ahead. Cover; chill.
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Brush scones lightly with milk; sprinkle with remaining 1 tablespoon sugar. 
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Bake until scones are crusty on top and tester inserted into center comes out clean, about 15 minutes (or up to 20 minutes if refrigerated).