Preheat the oven to 350oF.
To make the spicy tartar sauce, mix mayonnaise, lemon, horseradish, hot sauce, Dill relish, kosher salt, and ground black pepper in a small bowl. Then, keep it in the refrigerator.
In a large bowl, whisk eggs, hot sauce, seafood seasoning, and salt.
In another bowl, add cornmeal, flour, cornstarch, salt, and pepper and mix.
Marinate the catfish in the egg mixture. Then, put it in the flour mixture. Coat it with the mixture and shake off the extra flour.
Heat oil in a pan. Put the marinated fish into it. Fry until it turns golden for about 2 to 3 minutes.
After frying, place it on the paper towel and season it with salt.
Then, cut the sandwich rolls in half. Apply butter on the halves of the rolls.
Toast the rolls in the oven until they turn golden for about 8 minutes.
Take out the rolls and apply spicy tartar sauce to them. Then, put lettuce and catfish on the buns.
The catfish sandwich is ready and you can serve it immediately.