Place the chicken breast between two sheets of parchment paper and pound with a meat mallet until it is an even half-inch thickness.
Pour the buttermilk into a shallow bowl and submerge the chicken, letting it marinate for at least 15 minutes to tenderize.
In a separate shallow dish, whisk together the whole wheat flour, smoked paprika, garlic powder, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting the excess drip off, then dredge it thoroughly in the seasoned flour mixture until fully coated.
Heat the avocado oil in a non-stick skillet over medium heat and cook the chicken for 5-6 minutes per side until the crust is golden and the internal temperature reaches 165 degrees Fahrenheit.
Lightly toast the whole wheat bun in the same skillet or a toaster until warm and slightly crisp.
Assemble the sandwich by placing the cooked chicken on the bottom bun, followed by the romaine lettuce, tomato slices, and dill pickles before topping with the other half of the bun.