Preheat oven to 350 degrees. Line a jumbo muffin tin with paper liners or coat with nonstick cooking spray.
Zest both oranges. Squeeze 1 tablespoon of juice from an orange. Set aside.
In a large bowl, combine flour, baking powder, baking soda, cinnamon and salt.
In a separate bowl, combine the buttermilk, sugar, eggs, oil, orange juice, orange zest and vanilla.
Stir the wet ingredients into the dry ingredients until just combined. Fold in the cranberries. Fill the muffin tin 3/4 of the way full with batter. Sprinkle turbinado sugar over the tops of the muffins.
Bake 25 minutes until tops are golden brown, or until a toothpick inserted in the center of a muffin comes out clean. Cool to room temperature in the muffin tin.