Blend fresh parsley, fresh oregano, garlic, red wine vinegar, olive oil, red pepper flakes, and salt until smooth but slightly chunky, about 30-60 seconds. Stop once the mixture is cohesive with visible herb bits.

Season the chicken thighs with salt and pepper and brush them with half the chimichurri. Use a thin, even coating so the herbs adhere to the skin.

Marinate the chicken for 30 minutes to 2 hours in the refrigerator. Keep it covered so the surface stays moist while absorbing flavor.

Preheat the grill to medium-high heat. Aim for a steady heat so the thighs char without drying out.

Grill the chicken thighs for 6-7 minutes per side until the internal temperature reaches 165°F and the skin is crispy. Flip once and continue grilling until both sides are deeply browned with charred spots.

Let the chicken rest for 5 minutes before serving. This helps the juices redistribute so the thighs stay tender.

Serve the grilled chicken topped with the remaining fresh chimichurri. Spoon it generously so the bright green sauce contrasts with the charred surface.