01 - Pat the chicken thighs dry with paper towels to ensure proper seasoning adhesion and even cooking.
02 - In a large bowl, whisk together olive oil, apple cider vinegar, brown sugar, smoked paprika, garlic powder, onion powder, chili powder, salt, and black pepper until well combined.
03 - Add chicken thighs to the bowl and toss thoroughly to coat evenly with the spice mixture. Allow to marinate for at least 15 minutes, or up to 4 hours in the refrigerator for deeper flavor penetration.
04 - Preheat grill to medium-high heat or preheat oven to 400°F.
05 - Place chicken thighs on the grill skin-side down. Cook for 6-7 minutes until skin begins to crisp. Flip and brush generously with BBQ sauce. Continue grilling for 25-30 minutes, turning and basting with additional BBQ sauce every few minutes, until internal temperature reaches 175°F and chicken is cooked through with slight char marks.
06 - Arrange marinated chicken thighs on a foil-lined baking sheet, skin-side up. Roast for 30-35 minutes, brushing with BBQ sauce every 10 minutes during cooking, until internal temperature reaches 175°F.
07 - Remove chicken from heat and let rest for 5 minutes to allow juices to redistribute. Serve with additional BBQ sauce on the side if desired.