Prepare hot coals in a chimney or campfire. You'll need 24 coals for this recipe. Line a Dutch oven with parchment paper.
In a large bowl, whisk the flour, cornmeal, sugar, baking powder, salt, and baking soda together.
Combine the milk, egg, and oil in a small bowl or jug and pour it into the dry ingredients. Mix gently until everything is combined and no dry patches remain.
Scrape the batter into the prepared Dutch oven and cover with the lid.
Set up the Dutch oven for cooking with 8 coals underneath and 16 coals on the lid. Cook until the cornbread is puffed and a toothpick inserted into the center comes out clean, about 25 minutes.
Slice into wedges and serve warm.
Notes
Get ahead--Mix your dry ingredients in a resealable plastic bag before heading out on your camping trip.
Use parchment--Line your Dutch oven with parchment. It will make it easier to clean the oven after cooking and easier to lift the bread out of the hot Dutch oven. If you don't have parchment, be sure to butter the inside of your Dutch oven well.
Cooking time can vary--Since you're cooking in a Dutch oven outside, the cooking time can vary due to outside temperature and wind. If you're cooking on a very windy day, try to protect the Dutch oven with a barrier, such as a tarp.