Preheat oil in deep fryer to 350˚ F. Lay catfish fillets on the cutting board lengthwise in front of you. With a sharp knife, carefully cut the fish into thin fillets, as if you were butterflying it.
Continue to cut thin layers horizontally until you get 3 to 4 very thin pieces. In a bowl, mix together remaining ingredients. Dredge fish in cornmeal mixture, making sure to thoroughly coat the fish. Fry 4 to 6 pieces at a time for about 5 to 7 minutes or until golden brown. Drain on paper towels.
For the dressing, combine all ingredients in a container with a tight-fitting lid.
Shake container until all ingredients are incorporated. Toss lettuce with dressing right before you serve, and top with catfish.