In a large skillet over medium heat, brown the chicken thighs in the oil for about 10 minutes, turning to brown all sides.
Transfer the chicken thighs to the slow cooker insert. In a bowl, combine the ketchup, brown sugar, Worcestershire sauce, vinegar, mustard, cayenne, garlic powder, and salt. Pour over the chicken thighs.
Cover and cook on HIGH for 1 hour. Reduce heat to LOW and cook for about 5 hours longer. Remove the chicken thighs to a plate and shred. Return the shredded chicken to the sauce.
Spoon the shredded chicken and sauce mixture onto the toasted buns. Top with dill pickle slices and coleslaw, if desired.
Nutritional analysis for the shredded chicken with standard hamburger buns, toppings not included:
Calories per serving: 378
Fat per serving: 15.4