In a small mixing bowl whisk together the mayonnaise, sour cream, buttermilk, vinegar, garlic and pepper until combined. Stir in the blue cheese.
Use or store refrigerated in an airtight container until ready to use.
For the fried chicken:
Fill a large cast iron pan with vegetable oil so it reaches 2-inches up the pan. Heat the oil to 350°F (180ºC).
In a medium shallow bowl add the flour. Whisk the buttermilk and egg together in another medium bowl. Season chicken with salt and pepper. One piece at a time, dip chicken in the buttermilk mixture then dredge in the flour.
Shake off any excess flour and fry in the oil, flipping once, until the chicken is golden brown on all sides, about 8 minutes. Remove the chicken and allow to drain on a paper towel-lined plate or baking cooling rack.
When ready to serve, drizzle with buffalo sauce and toss to coat.
For assembly:
Add the celery to a medium mixing bowl and toss with ⅓ cup of the blue cheese dressing.
Add the buffalo coated fried chicken thighs to the bottom bun then top with celery slaw. Close the sandwiches and serve.
Video
Notes
For the crispiest chicken, let it rest on a wire rack after frying — not paper towels. This keeps the coating crunchy instead of soggy while you prep the buffalo sauce and slaw.