For the coleslaw: In a medium bowl, combine the coleslaw mix, red onions, radishes, and cilantro. In a small bowl, whisk together the lime juice, honey, salt, and pepper. Add to the coleslaw mixture, tossing gently to coat.
For the remoulade: In a small bowl, combine the sour cream, garlic, green onions, mustard, lemon juice, and dill. Cover and refrigerate until needed.
For the catfish: In a large Dutch oven, pour the oil to a depth of 2 inches and heat to 350 degrees F.
Cut the catfish into strips. Combine and whisk together the cornmeal and Cajun seasoning. Coat the catfish strips in the cornmeal mixture.
Fry the catfish, in batches if necessary, until golden brown, 2 to 3 minutes. Drain on paper towels. Place 2 to 3 catfish strips in the center of each Fried Taco Shell. Top each evenly with the coleslaw mixture. Dollop with the remoulade. Serve with sliced avocado and lime wedges, if desired.
Heat the oil in a Dutch oven to 350 degrees F.
Place the tortilla into the oil, folding into a taco shape using heatproof tongs. (You will have to hold its shape with the tongs while it fries.) Fry until golden brown, 2 to 3 minutes. Drain on paper towels.