Marinate the chicken: In a bowl, mix together buttermilk, garlic powder, paprika, salt, and pepper. Add chicken breasts and marinate for at least 30 minutes in the refrigerator
Make the spicy sauce: In a small bowl, mix together mayonnaise, sriracha sauce, honey, and apple cider vinegar. Set aside.
Make the pickles: In a small saucepan, bring vinegar, water, sugar, salt, peppercorns, garlic, and dill to a boil. Remove from heat and let cool. Add the sliced cucumbers to a jar and pour the pickling liquid over them. Let sit in the refrigerator for at least 30 minutes.
Bread the chicken: In a shallow dish, place flour. In another shallow dish, beat eggs. In a third shallow dish, place panko breadcrumbs. Dredge each chicken breast in flour, then egg, and finally panko breadcrumbs.
Fry the chicken: Heat oil in a large skillet over medium-high heat. Add chicken breasts and cook until golden brown, about 8-10 minutes - until the thickest piece registers 163 degrees. Remove from heat and let cool.
Assemble the sandwich: Toast the buns. Spread the spicy sauce on both sides of each bun. Add lettuce, tomato, pickles, and a chicken breast to each bun. Serve and enjoy!