In a small bowl, whisk together the Greek yogurt, avocado oil mayonnaise, lemon juice, lemon zest, and minced garlic to create the aioli.
In a separate small dish, combine the smoked paprika, garlic powder, onion powder, dried thyme, cayenne pepper, sea salt, and black pepper.
Pat the catfish fillets dry with a paper towel and coat both sides evenly with the spice mixture, pressing it into the flesh.
Steam the green beans for 5-6 minutes until they are tender-crisp and vibrant green.
Heat the avocado oil in a cast-iron skillet over medium-high heat until shimmering.
Place the catfish in the hot skillet and sear for 3-4 minutes per side until the crust is blackened and the fish flakes easily with a fork.
Serve the catfish immediately with a dollop of lemon aioli and the steamed green beans on the side.