In a small bowl, combine the smoked paprika, garlic powder, onion powder, dried thyme, sea salt, black pepper, and cayenne pepper to create the blackening seasoning blend.
Pat the catfish fillets completely dry with a paper towel and coat both sides evenly with the spice mixture, pressing gently so the seasoning adheres well.
In another small bowl, whisk together the Greek yogurt, Dijon mustard, lemon juice, capers, and hot sauce to prepare the zesty remoulade; set aside in the refrigerator.
Steam the green beans for 5-7 minutes until they are crisp-tender and bright green, then set aside.
Heat the avocado oil in a large cast-iron skillet or heavy-bottomed pan over medium-high heat until shimmering.
Place the catfish fillets in the hot skillet and sear for 3-4 minutes per side until the crust is dark and the fish flakes easily with a fork.
Plate the blackened catfish alongside the steamed green beans and serve immediately with a generous dollop of the prepared remoulade.