Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
Submerge the chicken in buttermilk in a shallow bowl and let it marinate for at least 15 minutes.
In a separate bowl, whisk together the almond flour, arrowroot powder, garlic powder, onion powder, sea salt, black pepper, and smoked paprika.
Remove the chicken from the buttermilk, allowing excess to drip off, then dredge thoroughly in the flour mixture until fully coated.
Lightly coat the chicken on both sides with the avocado oil and place it in the air fryer basket.
Air fry at 375°F for 12 to 15 minutes, flipping halfway through, until the coating is golden and the internal temperature reaches 165°F.
Toast the sprouted grain bun and assemble the sandwich with the crispy chicken, romaine lettuce, tomato slices, and dill pickles.