Preheat oven to 425°. Pour oil into a 10-inch cast-iron skillet. Place in oven until oil is very hot, about 8 minutes.
In a large bowl, whisk together cornmeal, flour, baking powder, and salt. In a medium bowl, whisk together buttermilk, melted butter, and eggs. Make a well in center of dry ingredients. Add buttermilk mixture; stir until combined. Carefully pour batter into hot oil in skillet.
Bake until golden brown and a wooden pick inserted in center comes out clean, about 27 minutes.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/buttermilk-cornbread/