Preheat the oil in a large cast iron or heavy bottomed pot, over medium heat. Cut the fillets, horizontally into strips, 1/2-inch thick. Season the fish with salt and pepper. Combine the flours and season with salt and pepper. Dredge each piece of fish in the flour, coating completely. Dip each piece in the egg wash, letting the excess drip off. Dredge the fish for a second time in the flour, coating completely. Fry the fish in batches until crispy, about 3 to 4 minutes. Remove and drain on paper towels. Season with salt and pepper. Serve the fish with lemon halves and tartar sauce and garnish with parsley.
Combine all ingredients in a bowl and stir to combine. Add lemon juice and salt, to taste. Refrigerate until thoroughly chilled.