Preheat oven to 450 degrees. Pour 1 teaspoon vegetable oil into a cast iron skillet, and place skillet in oven to heat for 5 minutes.

In a large bowl, stir together cornmeal and next 3 ingredients. Stir in eggs, 1 at a time, until just blended. Stir in buttermilk and 2 tablespoons vegetable oil. Pour batter into the preheated skillet and bake for 25 minutes.