Sweet Potato Cornbread

1/3 cup plus 2 tablespoons vegetable oil, divided
1 cup mashed sweet potatoes or 1 (15 ounce)
    can, drained and mashed)
3 large eggs
1 1/2 cups milk or buttermilk
3 cups self-rising cornmeal mix*
1/2 cup granulated sugar (optional)

Heat oven to 375 degrees F.

Put 2 tablespoons of oil into a cast-iron skillet and place skillet in oven to preheat.

Combine mashed sweet potatoes, eggs and milk in a large mixing bowl. Blend until smooth. Add remaining 1/3 cup oil; cornmeal; and, if desired, sugar. Stir until just combined. Pour into preheated skillet. Bake for 40 to 45 minutes or until golden brown.

Serve warm.

* 1 1/2 cups yellow cornmeal, 1 1/2 cups all-purpose flour, 1 tablespoon plus 1 1/2 teaspoons baking powder and 3/4 teaspoon salt, combined, may be substituted for the self-rising cornmeal mix.