Peel the potatoes and slice into ¼” thick slices.
Peel and thinly slice the onion.
Place foil on the counter and spray with a non-stick cooking spray. I used 1 piece of foil per each potato.
Place the potatoes and onion slices on the foil. Season each packet with approximately ¼ tsp of the Salt and Pepper and top with 1 Tablespoon of the butter.
Fold each foil packet close and seal tightly .Grill over medium-high heat for 30-40 minutes until the potatoes are soft. Remove the heat, be careful when opening the foil packet and enjoy!
