Place the chicken breast in a shallow bowl and pour the buttermilk over it, allowing it to marinate for at least 15 minutes.
In a separate wide bowl, whisk together the almond flour, arrowroot powder, garlic powder, onion powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting any excess liquid drip off, then dredge it thoroughly in the flour mixture until fully coated.
Lightly mist the coated chicken on both sides with avocado oil and place it into the air fryer basket.
Cook at 400 degrees Fahrenheit for 12 to 15 minutes, flipping halfway through, until the exterior is golden and the internal temperature reaches 165 degrees.
While the chicken is cooking, steam the green beans until they are vibrant and tender-crisp to serve as a fresh side.