Preheat the grill to medium-high heat or the oven to 400°F (200°C).

In a mixing bowl, combine the ground beef, mixed vegetables, diced potatoes, ranch dressing mix, olive oil, salt, and pepper. Mix well.

Cut four large pieces of aluminum foil, about 12 inches long. Place an equal amount of the beef mixture in the center of each piece of foil.

Fold the sides of the foil over the mixture and seal tightly to form packets.

Place the foil packets on the grill or in the oven. Cook for about 30-35 minutes, or until the beef is cooked through and the potatoes are tender.

Carefully open the packets (steam will escape) and serve hot.