Mix the buttermilk brine ingredients together in a large bowl. Add the chicken breast to the brine. Cover the bowl. Refrigerate up to four hours. (I usually just let my chicken brine overnight for maximum tenderness.)
When ready to cook the chicken breast, Pour cooking oil into a deep fryer. Use the amount of grease per the manufacturer guide. Heat the oil until it reaches 325 to 350 degrees.
While the oil heats up, Mix the flour ingredients together in a ziploc bag.
Deep the chicken breasts into the flour mixture.
To double dip and get a nice crunchy coating, at this time you can dip the chicken breast into the additional buttermilk and then dip the chicken back into the flour mixture. Let the chicken rest for about 5 to minutes while your grease heats to the proper temperature.
To make the slaw, chop your jalapenos and cilantro and set aside. Mix the buttermilk for the slaw, sugar, mayonnaise, rice vinegar together in a medium bowl. Then mix in the slaw mix, chopped jalapenos and cilantro. Salt and pepper to taste. Place in refrigerator until ready to use.
Place chicken breast into the deep fryer and fry for 7 to 8 minutes or until the internal temperature of the meat reaches 165 degrees when you insert a cooking thermometer into the thickest part of the meat.
After the chicken cooks. Let the chicken rest on a cooling rack for about 5 minutes. (The cooling rack keeps the crispy skin from getting soggy.)
Assemble the sandwiches then serve immediately.