In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, dried oregano, dried thyme, cayenne pepper, sea salt, and black pepper.
Pat the catfish fillets completely dry with paper towels to ensure a crispy exterior, then rub the spice blend generously onto both sides of the fish.
Heat the avocado oil in a large cast-iron skillet over medium-high heat until it begins to shimmer.
Carefully place the catfish 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 is searing, prepare the remoulade by whisking together the Greek yogurt, Dijon mustard, lemon juice, minced capers, and chopped fresh parsley.
Steam the green beans in a small pot with two tablespoons of water for 4 to 5 minutes until they are bright green and tender-crisp.
Plate the blackened catfish alongside the steamed green beans and top the fish with a generous dollop of the zesty remoulade.