Heat the oil to 350 degrees F (180 degrees F). You can use a deep fryer to set the temperature of the oil (Recommended method). If not using a deep fryer, you can fill a pot or large pan with about 2 inches of oil and use a heat-resistant thermometer to measure the temperature.
Season the pieces of fish with salt and pepper to taste on both sides.
In a shallow bowl place ½ cup (60 g) of the all-purpose flour.
To make the batter, whisk the buttermilk with the egg in a separate bowl.
To make the breading, mix the remaining ½ cup (60 g) of all-purpose flour with the cornmeal, seafood seasoning, garlic powder, cayenne pepper, baking powder, and baking soda in a third bowl.
Dust the fish with the flour that you placed in the first bowl. This will help the batter adhere to the fish. Then, dip the pieces of fish in the egg batter. And, finally, coat the fish with the seasoned breading.
Fry the fish in batches for 5-6 minutes or until golden brown if using a deep fryer. If using a pan, you can fry it over medium-high heat for 3 minutes on each side.
Remove the fish from the oil, drain it over paper towels, and sprinkle with salt to taste before serving.