Pat the catfish fillet completely dry with paper towels to ensure a proper sear.
In a small bowl, combine the smoked paprika, garlic powder, onion powder, dried thyme, dried oregano, cayenne pepper, sea salt, and black pepper.
Generously coat both sides of the catfish with the spice blend, pressing it into the flesh.
Heat a cast-iron skillet over medium-high heat and add the ghee, allowing it to melt and begin to shimmer.
Place the catfish in the hot skillet and sear for 3 to 4 minutes per side until a dark crust forms and the fish flakes easily with a fork.
While the fish cooks, steam the green beans in a small amount of water for 5 minutes until tender-crisp.
In a small ramekin, whisk together the Greek yogurt, lemon juice, and minced garlic to create the aioli.
Serve the blackened catfish immediately with the green beans and a dollop of the lemon aioli.