Combine the salt, paprika, black pepper, cayenne, garlic powder, cumin, oregano, and thyme in a small bowl, then sprinkle evenly onto catfish fillets and set aside while preparing the "crema."
Combine the sour cream, lime zest, lime juice, garlic, basil, and chipotle pepper in a small food processor and process until smooth. Refrigerate until ready to use.
Place a cast-iron skillet over high heat. When you think it's really hot, leave it for a few more minutes. If you turn the lights off and it glows...you're ready.
Add the catfish to the pan and cook until crisped and blackened, about 1 minute. Flip and cook another minute, then rest on a plate off the heat for 1 minute. The fish should be opaque inside and flake easily when broken with a fork.
Turn the heat off and use the residual heat to heat the tortillas or, if you like a little more char, lay them one at a time right over gas burners set to low for about 30 seconds per side.
Break up the cooked fish into several pieces and serve inside the tortillas topped with the tomatoes, lettuce, and "crema"If you like your crema extra tangy, add some yogurt to it. mixture.