Slice the chicken breast into even 1-inch thick strips or tenders.
Place the chicken strips in a shallow bowl and pour the buttermilk over them, ensuring they are fully submerged; marinate for at least 20 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 each chicken strip from the buttermilk, letting the excess drip off, then dredge thoroughly in the flour mixture until well-coated.
Preheat your air fryer to 400°F and lightly mist the basket with avocado oil.
Arrange the chicken in a single layer in the basket, spray the tops of the chicken with the remaining avocado oil, and cook for 12-15 minutes, flipping halfway through, until golden and crispy.
While the chicken cooks, steam the green beans in a steamer basket over boiling water for 5-7 minutes until they are tender-crisp and bright green.
Serve the crispy chicken immediately alongside the steamed green beans.