In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, oregano, thyme, cayenne, salt, and pepper to create the blackening seasoning.
Pat the catfish fillets completely dry with a paper towel and rub the spice mixture evenly over both sides of the fish, pressing gently so it adheres.
Heat the avocado oil in a cast-iron skillet over medium-high heat until the oil is shimmering and just starting to smoke.
Place the catfish in the hot skillet and sear for 3 to 4 minutes per side until the spice crust is dark and the fish flakes easily with a fork.
While the fish cooks, whisk together the Greek yogurt, Dijon mustard, lemon juice, and hot sauce in a small ramekin to create the remoulade.
Steam the broccoli florets in a steamer basket over boiling water for 4 to 5 minutes until tender-crisp and bright green.
Serve the blackened catfish immediately topped with a dollop of the tangy remoulade and the steamed broccoli on the side.