Pat the catfish fillets completely dry using paper towels to ensure a proper sear.
In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, cayenne, thyme, oregano, salt, and pepper.
Coat both sides of the catfish fillets generously with the spice mixture, pressing it into the flesh.
Heat the avocado oil in a cast-iron skillet over medium-high heat until it begins to shimmer.
Place the fillets in the hot skillet and sear for 3 to 4 minutes per side until the crust is dark and the fish flakes easily with a fork.
While the fish cooks, steam the green beans in a steamer basket for 5 to 6 minutes until they are tender-crisp and bright green.
In a small ramekin, combine the mayonnaise, Dijon mustard, lemon juice, and hot sauce to create the remoulade.
Plate the blackened catfish alongside the steamed green beans and serve with a dollop of the Cajun remoulade.