Season the chicken with the mixed herbs and black pepper. Heat the oil in a large pan over a medium-high heat and cook the chicken breasts, skin-side down, for 1 minute. Turn down the heat and cook for 20-25 minutes, until the skin is crisp. Turn and cook for another 5 minutes, until cooked through and no pink remains.
Meanwhile, melt the butter in another frying pan, add the leeks and cook, stirring, for 5 minutes until soft. Add the carrot ribbons for the final minute.
While the veg is cooking, tip the lentils in brine into a small pan and heat through. Drain, then squeeze over the juice from half a lemon (cut the other half into extra wedges to serve). Season with pepper.
Serve the chicken with the lentils and vegetables with the lemon wedges on the side to squeeze over.