Preheat the oven to 450F.

Pour 2 tablespoons of the oil into a well-seasoned 9-inch cast-iron skillet (see Note) and place over medium-high heat.

Put the cornmeal in a large mixing bowl.

Make a well in the cornmeal and add the remaining 2 tablespoons oil.

With a fork, stir in enough of the buttermilk to make a batter that is thick but can be easily poured into the hot skillet.

You may not need all 3 cups.

Carefully pour the batter into the skillet.

The oil will come up around the edges.

Use the back of a spoon to smooth this over the top of the batter.

Continue to heat on the stovetop for 1 minute, and then transfer the skillet to the oven and bake the corn bread for 20 minutes, or until browned on top.

Immediately turn the cornbread out onto a cooling rack to keep the crust crisp.

Season a new cast-iron skillet by coating the inside with vegetable shortening (not butter) and heating the pan in a very hot oven (450F) for 1 hour.

Cool the skillet and wipe off any excess oil before using.

To care for a seasoned skillet, wipe the interior after each use.

Do not soak it in soapy water or put it in the dishwasher.