Preheat the grill to 350°F (for my gas grill this means all burners on low to get an even heat) If you are using charcoal, you will want to light them, then let them cool off slightly to achieve an even, low heat. Once the grill is to temperature, place a 9-inch cast iron skillet in the grill to preheat.
Grate the corn and keep as much of the liquid as you can.
In a large bowl, whisk together the cornmeal, flour, sugar, baking powder, salt, and baking soda. In a small bowl combine the buttermilk, egg yolk, corn and oil. Add the wet to the dry and stir to combine. In a clean bowl, whisk the egg white until stiff peaks. Gently fold the egg white into the batter.
Add two tablespoons of butter to the pan, shut the lid for a minute and let the butter melt, but not color.
Pour the corn bread batter into the hot pan.
Shut the lid of the grill and bake for about 18 to 25 minutes, depending on your grill. Remove the corn bread from the grill while you prepare the peaches.