Lemon and Herb Roast Chicken and Vegetables

small red-skinned potatoes, quartered

medium carrots, cut into 1-inch pieces

stalks celery, peeled and cut into 1-inch pieces

medium red onion, cut into 1/2-inch wedges

olive oil

Kosher salt and freshly ground black pepper

bone-in, skin-on chicken breasts (about 1 3/4 pounds)

poultry seasoning

lemon, halved

chopped fresh parsley