Step 1: Slice the green tomatoes into 1/4 to 1/2-inch thick rounds. Lay them on paper towels and lightly sprinkle with salt. Let them sit for 10-15 minutes to draw out moisture, then blot dry with fresh paper towels.
Step 2: In a shallow dish, combine the all-purpose flour, 1 teaspoon salt, black pepper, garlic powder, onion powder, and paprika. Whisk well.
Step 3: Pour the buttermilk into a second shallow dish.
Step 4: In a third shallow dish, combine the yellow cornmeal and cayenne pepper (if using).
Step 5: Heat 1 inch of oil in a large, heavy-bottomed skillet (like cast iron) over medium-high heat to 350-375°F (175-190°C).
Step 6: Dredge each tomato slice first in the seasoned flour, shaking off excess.
Step 7: Dip the floured slice into the buttermilk, letting excess drip off.
Step 8: Finally, coat generously in the cornmeal mixture, pressing gently to adhere.
Step 9: Carefully place coated tomato slices into the hot oil, without overcrowding the pan. Fry in batches if necessary.
Step 10: Fry for 3-4 minutes per side, or until golden brown and crispy.
Step 11: Transfer fried green tomatoes to a wire rack lined with paper towels to drain excess oil.
Step 12: Serve immediately with your favorite dipping sauce, such as remoulade, ranch, or spicy aioli.