Preheat the oven to 350° F and line a shallow baking pan with foil.
In a shallow dish, whisk together the egg and milk. Combine the cornmeal, 1-1/2 teaspoons salt and a few grinds of black pepper on a large plate or sheet of wax paper. Dip each catfish fillet into the egg mixture, drain off the excess, then coat thoroughly with the cornmeal.
Add about 1/8-inch of oil to the bottom of a large frying pan and heat over medium-high heat. Add the catfish fillets and cook until the coating is crisp and lightly browned, 1-1/2 to 2 minutes per side.
Transfer the fish to the prepared baking pan and place in the oven for 8 to 10 minutes.
While the fish finishes in the oven, make the sauce. Wipe out the pan, add the butter and melt over medium heat.
Add the green pepper and sauté until softened, 3 to 4 minutes, then add the garlic and scallions and continue cooking for an additional 1-1/2 minutes, stirring constantly.
Stir in the tomato sauce and add hot sauce to taste (see notes below). Add a pinch of sugar if desired and continue cooking for an additional 3 to 4 minutes, stirring occasionally.
Plate individual servings of fish and transfer the sauce to a serving bowl to pass at the table.
Tips for Making This Recipe
Frank's Red Hot is our favorite hot sauce for this dish. We generally go easy on the heat so we start with just 3/4 teaspoon and work up from there.