Mix the buttermilk, yogurt, and salt together until well combined. Add the chicken to the resealable bag, and pour the buttermilk mixture over it. Press the air out of the bag, ensuring that the mixture is evenly distributed. Place the bag on a small sheet pan or inside a mixing bowl, and leave it to marinate overnight on the lowest shelf of your refrigerator, turning once or twice if you think of it.

Remove chicken an hour before you are ready to roast, so that it can come to room temperature. Place the chicken on a roasting rack, and let the buttermilk drain over your sink (do not rinse the chicken). Gently pat dry with paper towels.

Season the chicken with black pepper on both sides. It will not require salt, since it was brined in a salt mixture.

Preheat your oven temperature to 425ºF or 220ºC (if you have a convection oven, use the convection bake setting, which will more evenly distribute the hot air).

In a roasting pan that will fit your roasting rack, roughly chop your vegetables into large-ish, bite-sized pieces, and mix them together in the pan. Add the wine or stock (the pan should be large enough so that the wine does not completely cover the vegetables). Season the vegetables with salt and pepper.

Place the chicken and rack on top of the vegetables. You may tie the legs with kitchen string if desired.

Roast the chicken on the center rack of the oven for 20 minutes, then lower the temperature to 400ºF (200ºC) and continue roasting for 10 minutes. Remove the chicken from the oven at this point, and return the temperature to 425ºF (220ºC).

Turn the chicken over so that it is now breast-side up, roast for another 20 minutes, lower the temperature again to 400ºF (200ºC) and roast for 10-15 minutes more, or until a thermometer inserted into the deepest part of the thigh reaches 165ºF (74ºC) and the juices run clear.

If at any point during roasting the skin becomes too dark, you may tent it with aluminum foil. Allow the meat to rest for at least 15 minutes before serving.