Cut the carrots lengthwise into quarters. Cut the onions into large slices. Par-boil the potatoes for 8-10 minutes, then cut them into halves or quarters depending on size.
Arrange the vegetables in a baking dish, add some water, lay out the chicken pieces, and cover tightly with foil.
Bake at 200°C (400°F) for 30 minutes covered with foil, then remove the foil and bake for another 15 minutes uncovered until the chicken reaches 74°C (165°F) internal temperature.