01 - Pat chicken thighs thoroughly with paper towels to remove surface moisture.
02 - Combine olive oil, apple cider vinegar, brown sugar, smoked paprika, garlic powder, onion powder, chili powder, salt, and black pepper in a large mixing bowl. Add chicken thighs and toss until completely coated. Let marinate for a minimum of 15 minutes, or up to 4 hours for intensified flavor.
03 - Heat a grill to medium-high, or preheat an oven to 400°F.
04 - For grilling: Place chicken thighs skin-side down on the hot grill. Cook for 6 to 7 minutes, then flip. Brush generously with barbecue sauce and continue grilling, turning and basting often, until the meat is cooked through and lightly charred with an internal temperature of 175°F (approximately 25–30 minutes total). For oven method: Place thighs skin-side up on a foil-lined baking sheet. Roast for 30–35 minutes, brushing with barbecue sauce every 10 minutes.
05 - Allow chicken to rest for 5 minutes before plating. Serve with additional barbecue sauce if desired.