Warm up your grill to medium heat (around 400ºF).
Place all ingredients into a very large bowl and toss together so that it is well-mixed and evenly coated.
Divide the mixture between the four pieces of foil, equating to a heaping cup for each one. Place it in the center of the foil.
Fold two sides of the foil in toward the center and fold together/down until you reach the veggies. Press flat.
Take one of the other sides and roll in, toward the center; repeat on the other side, until you have a packet. Press firmly on the rolls/folds so that they do not come apart easily.
Put them on the grill and lower the lid, grilling for 8 minutes on each side of the packet.
You can see if they're ready by peeling back a fold and checking the corn or potatoes.
For a drier mixture inside, open up the top of the packets while grilling during the last 4 minutes.
Serve hot, and top with a little more salt and pepper, hot sauce, or BBQ sauce if you desire! And if you have access to fresh green onions or cilantro, those would also be excellent on top.
