Restaurant-Quality Fried Catfish

Name: Restaurant-Quality Fried Catfish
Prep time: 10 min
Cook time: 10 min
Total time: 20 min
Cuisine: American
Ingredients: 4 fillets catfish (a little over a pound, total); 1½ cups oil (vegetable, canola or peanut (you may need more or less; depends on how deep your skillet is)); 2 cups cornmeal (yellow, not self-rising); 1 cup buttermilk; 1 tablespoon cayenne pepper ((red pepper, ground)); 1 teaspoon salt; 1 teaspoon black pepper; 1 cup mayonnaise; 2½ tablespoons relish (, (dill or sweet); squeezed in a paper towel); ¼ teaspoon onion; ¼ teaspoon garlic powder; ¼ teaspoon sugar; ¼ teaspoon salt; 1 teaspoon vinegar (or lemon)