Wash the carrot top leaves thoroughly under running water. Pat dry with kitchen/paper towel. Divide in two parts. Chop one half of the leaves finely.
Wash coriander leaves and stems thoroughly to remove any grit. Pat dry with kitchen/paper towel.
Grind garlic, coriander stems, coriander leaves, half of carrot top leaves (whole), chili, and salt to fine paste.
Marinate chicken thighs and carrots with chimichurri for 15 minutes at least.
Heat a grill pan and apply olive oil with pastry brush. Grill chicken and both sides till its cooked thoroughly and nice grill marks are seen on chicken. Baste chicken at intervals with olive oil. Similarly, grill the carrots.