Preheat oven to 400°F. Grease cast-iron skillet with vegetable or bacon grease and place in the oven to get it preheated.
In a medium mixing bowl add the flour, cornmeal, baking soda, baking powder, salt, and sugar. Whisk to combine well.
In a small bowl combine buttermilk, eggs, and oil. Make a well in the center of your dry ingredients and add wet ingredients. Stir just until the mixture comes together. There will be a few lumps remaining.
Add the Hatch green chiles to the batter and gently stir until evenly distributed.
Pour the batter into the preheated cast iron skillet and bake for 20-25 minutes until the top is a deep golden brown and a toothpick inserted into the center comes out clean.
Allow cornbread to cool slightly before serving.