Pat the catfish fillets completely dry with paper towels to ensure a proper sear.
In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, oregano, thyme, cayenne, sea salt, and black pepper.
Coat both sides of the catfish fillets generously with the spice rub, pressing it into the flesh.
Prepare the aioli by mixing the Greek yogurt, avocado oil mayo, lemon juice, lemon zest, and one minced garlic clove in a small ramekin.
Heat the avocado oil in a large cast-iron skillet over medium-high heat until it begins to shimmer.
Place the catfish 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, steam the green beans for 4 to 5 minutes until they are bright green and tender-crisp.
Plate the blackened catfish alongside the steamed green beans and serve with a generous dollop of the lemon aioli.