1 1/2 cups cornmeal
1/2 cup flour
1 tsp salt
1 tsp baking soda
2 cups buttermilk
Mix it all together until smooth. Pour into a black iron skillet that has been greased with butter or bacon fat. Bake in a 425-degree oven until top is brown and firm.
A little more elaborate (from Simply Recipes):
1 tablespoon bacon drippings
2 cups cornmeal OR 1 1/2 cups cornmeal and 1/2 cup flour
1 teaspoon baking soda
1 teaspoon salt
1 tablespoon sugar (optional)
1 large egg (optional)
1 1/4 cups buttermilk
6 tablespoons unsalted butter, melted
Preheat pan with bacon drippings: Put the bacon drippings in a 9 or 10-inch well-seasoned cast iron skillet and put the skillet into the oven. Then preheat the oven to 400°F with the skillet inside. (If you don’t have an iron skillet, you can use an uncovered Dutch oven or a metal cake pan.)
Make the batter: Whisk together all the dry ingredients (cornmeal, baking soda, salt, sugar if using) in a large bowl. In another bowl, beat the egg (if using) and buttermilk until combined, then mix that into the bowl of dry ingredients. Stir in the melted butter.
Pour batter into hot skillet and bake: When the oven is hot, take out the skillet (carefully, as the handle will be hot!). Add the cornbread batter and make sure it is evenly distributed in the skillet.
Bake at 400°F for about 20 minutes, or until the edges are beginning to brown and a toothpick inserted in the center of the bread comes out clean.
4 Rest bread in skillet, then serve: Let the bread rest for 10 to 30 minutes in the skillet before cutting it into wedges and serving.
To store, let the cornbread cool, then remove from pan and wrap in plastic wrap or transfer to an airtight container. Store at room temp for 2 to 3 days