Fried Green Tomatoes

1   large egg, lightly beaten 
1/2 cup  buttermilk 
1/2 cup  self-rising cornmeal mix 
1/2 teaspoon  salt 
1/2 teaspoon  pepper 
1/2 cup  all-purpose flour 
3  medium green tomatoes, 1/3-inch-thick slices 
Vegetable oil

Whisk together egg and buttermilk. Combine cornmeal mix,
salt, pepper, and 1/4 cup flour in a shallow dish. Dredge
tomato slices in remaining 1/4 cup flour; dip in egg mixture,
and dredge in cornmeal mixture. Pour oil to a depth of 1/2
inch in a large cast-iron skillet; heat to 375° over medium-high
heat. Drop tomatoes, in batches, into hot oil, and cook 2
minutes on each side or until golden. Drain on paper towels.
Sprinkle hot tomatoes with salt to taste.