Pound chicken breasts to even thickness (about 1/2 inch). Place in a bowl, cover with buttermilk, and refrigerate for at least 30 minutes (or up to 4 hours).
In a shallow dish, mix flour, paprika, garlic powder, salt, and pepper. Remove chicken from buttermilk, letting excess drip off, and dredge in flour mixture, pressing to adhere.
Heat about 1/2 inch oil in a large skillet over medium-high heat to 350°F. Fry chicken in batches until golden and cooked through (internal temp 165°F), about 4-5 minutes per side. Drain on paper towels.
In a bowl, combine cabbage, carrot, mayonnaise, vinegar, and sugar. Toss well and season with salt and pepper to taste.
Toast buns if desired. Place a chicken breast on each bottom bun, top with coleslaw, and close with top bun. Serve immediately.
Tips
For extra crunch, use panko breadcrumbs instead of flour.
Leftover coleslaw keeps in the fridge for up to 2 days.
To reduce oil absorption, ensure oil is hot enough before frying.