Wash potatoes, and cut them into quarters. Place potato quarters into a bowl of water. Prepare seasoned flour by combining 2 cups of flour, 1 teaspoon ground black pepper, 1 teaspoon salt, and 1 teaspoon garlic salt together in a bowl. Place 2 cups of buttermilk in another bowl. Batter potatoes by placing them in the seasoned flour, shake off excess flour. Place potatoes into the buttermilk, and coat the potatoes well. Place potatoes back into the seasoned flour and coat well. Shake off excess flour. Place the potatoes on a wire rack to rest for about 5 minutes before cooking. Preheat oil in a deep fryer to 350 degrees. Cook potatoes for 8 to 12 minutes or until they are brown, and they float. Drain on a clean wire rack.