Preheat oven to 450 degrees F (225 degrees C). Melt the shortening in a 9 inch round iron skillet in the heating oven.
In a large bowl, stir the cornmeal, salt and baking soda together. Stir in the egg and buttermilk.
Remove skillet from the oven and pour the batter into the skillet, stirring the melted shortening into the batter.
Bake in the preheated oven for 30 to 40 minutes. Remove from oven when top of cornbread is brown and it feels firm to the touch. Turn out on to a serving plate. Cut into wedges and serve immediately with butter.