Slice the chicken breast into a flat cutlet and pat dry with a paper towel to ensure the coating sticks.
In a shallow bowl, whisk together the almond flour, garlic powder, smoked paprika, sea salt, and black pepper.
Lightly brush the chicken with a thin layer of mustard, then dredge it in the almond flour mixture until evenly coated.
Mist the chicken with avocado oil and air-fry at 375°F for 12-15 minutes, flipping halfway through, until the crust is golden and crispy.
While the chicken cooks, whisk together the remaining mustard, honey, and Greek yogurt in a small bowl to create the sauce.
Toast the sprouted grain bun until warm, then assemble the sandwich with the crispy chicken, lettuce, tomato, and a generous drizzle of the honey-mustard sauce.