Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
Place the chicken in a shallow bowl with the buttermilk and let marinate for 15 minutes.
In a separate shallow dish, whisk together the almond flour, arrowroot starch, garlic powder, onion powder, paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing excess to drip off, then dredge in the flour mixture, pressing firmly to ensure an even coating.
Lightly grease the air fryer basket with avocado oil and place the chicken inside.
Cook at 375°F for 12-15 minutes, flipping halfway through, until the exterior is golden brown and the internal temperature reaches 165°F.
Lightly toast the sprouted grain bun in a pan or toaster.
Assemble the sandwich by placing the lettuce, tomato, and pickles on the bottom bun, followed by the crispy chicken and the top bun.