Chop herbs on a cutting board carefully.
Place herbs, garlic in a mixing bowl.
Add olive oil and red wine vinegar slowly.
Add salt, pepper, chili flakes, oregano, lemon juice.
Whisk until ingredients are well combined.
Place chicken thighs in a large bowl.
Pour half chimichurri over the chicken thighs.
Coat chicken well with chimichurri marinade.
Marinate for 30 minutes or overnight.
Preheat grill to medium-high heat carefully.
Place chicken thighs skin side down first.
Grill for 6 minutes on each side.
Cook until juices run clear completely.
Remove chicken from grill to a plate.
Brush with remaining chimichurri sauce generously.
Serve hot with your favorite sides immediately.