Combine marinade ingredients and add to gallon zippered bag. Add chicken to bag and let sit for at least 30 minutes (up to 24 hours).
Prepare remaining ingredients. Preheat grill or smoker to medium-high.
In a large cast iron skillet over medium-high heat, add pieces of chicken (reserve marinade). Cook for 4 minutes on each side. Add reserved marinade to pan. Sprinkle with half of sesame seeds and add half of orange slices.
Loosely cover skillet with aluminum foil. Place covered skillet on center of grill or smoker and close lid. Let cook (undisturbed) for 30 minutes. Remove foil and cook another 10 minutes.
Remove from grill and sprinkle with remaining sesame seeds and remaining orange slices.