Unfortunately, the potatoes reacted to being exposed to air by turning gray. When first cutting up a potato, we recommend that you place the pieces immediately into a solution of water and something acidic such as a tablespoon of concentrated lemon juice to a gallon of water. In addition, when the potato is heated up in a closed space at a temperature below 325 degrees, this contributes to the graying of the potatoes. They may also have reacted to the foil.

If the packet of foil stayed intact, I would toss the spuds and still use the chicken. If you have any leftover unpeeled potatoes, you can microwave them until they’re tender and add them back into your completed dish.