Preheat your grill or grill pan over medium-high heat to ensure it’s hot enough to sear the chicken and develop a crispy skin.
Rub the chicken thighs generously with salt and pepper, then brush lightly with olive oil to promote crispiness and prevent sticking.
Place the chicken skin-side down on the hot grill, pressing down gently to ensure good contact. Grill for about 6-8 minutes until the skin is golden and crispy, then flip and cook for another 8-10 minutes until cooked through and juices run clear.
While the chicken sizzles, combine the chopped parsley, minced garlic, lemon zest, orange zest, red pepper flakes, vinegar, and remaining olive oil in a mixing bowl. Whisk everything together until you have a bright, slightly chunky sauce; taste and adjust salt and pepper as needed.
Once the chicken is cooked and crispy, transfer it to a serving plate and brush it with a little more olive oil. Let it rest for a few minutes to tenderize and allow the flavors to settle.
Finish by spooning the fresh citrus chimichurri generously over the hot chicken, allowing the vibrant herbs and citrus to soak into the crispy skin.
Serve hot, perhaps with crusty bread or rice to soak up the flavorful sauce and enjoy the bright, herbaceous flavors with every bite.