Heat the oil in a wide-bottomed pan, sauté the onions, add the carrots and continue to cook. Pour in the orange juice, cover and simmer for approx. 20 mins. until soft, season.
Cut a 4 cm pocket lengthwise in the chicken breasts. Coat the mozzarella sticks in the parsley and stuff the chicken breasts. Heat the oil in a non-stick frying pan, reduce the heat. Fry the chicken breasts for approx. 7 mins. on each side, season.