In a bowl, mix together the buttermilk and chicken pieces. Cover and leave in the fridge for 2 hours or overnight, if possible.
When you are ready to cook the chicken, heat a large high-sided pot over a medium heat and fill with 3-4 inches of oil- heat to 350˚F. Mix the flour, oregano, paprika, cayenne pepper, garlic powder, sea salt and ground black pepper on a large plate.
Remove the chicken pieces from the buttermilk and dredge in the seasoned flour. Shake off any excess, then place the chicken in the pan to fry. Cook for about 5 minutes on either side until they are cooked through and have a good golden brown colour. Remove from the pan using a slotted spoon and drain on a plate lined with kitchen paper.
Mix together the mayo with a few drops of chipotle hot sauce.
Assemble the sandwiches by spreading a dollop of hot mayo across one bun and a dollop of guacamole on the other. Pile up the sandwich with, lettuce, streaky bacon and chicken and press together. Enjoy!