Preheat oven to 450 degrees. Heat shortening in an iron skillet, muffin pan, or other baking pan. Combine cornmeal, flour, and salt in a mixing bowl. In a separate bowl, combine buttermilk, milk, and egg. Add baking powder and baking soda. Stir. Add ¼ cup melted shortening, stirring constantly. Pour into hot pan, smoothing surface with spatula. Bake for 20 to 25 minutes or until golden brown on top.