Slice the chicken breast into even 1-inch wide strips.
Place the chicken in a shallow bowl and pour the buttermilk over it, ensuring every piece is coated; let marinate for 20 minutes.
In a separate wide dish, whisk together the almond flour, arrowroot starch, garlic powder, onion powder, smoked paprika, sea salt, and black pepper.
Remove each chicken strip from the buttermilk, letting excess drip off, then dredge thoroughly in the flour mixture until fully coated.
Preheat your air fryer to 400°F and lightly spray the basket with avocado oil.
Place the chicken in the basket in a single layer and spray the tops of the chicken with the remaining avocado oil.
Air fry for 12-15 minutes, flipping halfway through, until the coating is golden brown and the chicken is cooked through.
While the chicken cooks, steam the green beans for 5-7 minutes until tender-crisp and bright green.
Serve the crispy chicken immediately alongside the steamed green beans.