01 - In a large mixing bowl, whisk together olive oil, lemon juice, smoked paprika, garlic powder, onion powder, oregano, thyme, cayenne pepper, black pepper, salt, and brown sugar until thoroughly combined.
02 - Add chicken thighs to the bowl and toss until evenly coated with the spice mixture. Cover and refrigerate for minimum 30 minutes, up to 8 hours for enhanced flavor penetration.
03 - Heat grill or grill pan to medium-high temperature. Lightly oil the cooking grate to prevent sticking.
04 - Remove chicken from marinade, allowing excess to drip off. Grill thighs for 6 to 8 minutes per side until internal temperature reaches 165°F and exterior develops charred, crispy marks.
05 - Transfer grilled chicken to a serving plate and let rest for 5 minutes to redistribute juices. Garnish with fresh parsley and accompany with lemon wedges.