Preheat oven to 400°F. Grease 6 large or twelve regular muffin cups. Mix first 6 ingredients in large bowl. Whisk buttermilk, oil, egg and lemon zest in small bowl. Add to dry ingredients and stir just until blended. Let stand 15 minutes at room temperature. (Batter can be prepared ahead of time. Refrigerate up to 3 days.) Add to batter, apples and nuts and mix briefly. Gently fold in berries. Fill muffin cups 2/3 full. Bake about 25 minutes or until tester comes out clean. Cool in the muffin tin about 5 minutes then turn out on wire rack.