Remove the capon from the refrigerator 30 minutes prior to cooking. Preheat the oven to 450°F and coat a roasting pan and rack with nonstick spray.

Cut the onion into 2 wedges and chop the carrot and celery into 3 or 4 pieces each. Place them in the center of a square of cheesecloth, add the parsley and garlic and gather up the edges to make a bag. Secure with kitchen twine.

Season the cavity of the capon with salt and pepper, then place the bag of aromatics inside.

Truss the capon by looping a length of twine under the tailbone and around the ends of the legs, cinching in the center to bring them together in front of the cavity. Fold the wing tips under and position the capon on the roasting rack.

Drizzle the capon with olive oil and use your hands to rub it in, being sure to get in between the legs and the body. Season liberally with salt and pepper.

Add the wine to the roasting pan along with enough water to bring the depth to about 1/2 inch.

Roast the capon for 30 minutes at 450°F, then lower the temperature to 350°F. Baste the capon with the pan juices and return to the oven.

Continue roasting, basting every 15 minutes, until an instant read thermometer placed in the thickest part of the thigh registers 165°F. Total roasting time (including the 30 minutes at 450°F) for a 7 lb capon should be about 2 hours (17 minutes per pound).

Allow the capon to rest for 15 minutes before carving.