01 - Build your campfire or preheat a grill to medium-high heat.
02 - In a large bowl, combine ground beef with salt, pepper, garlic powder, and smoked paprika. Mix until evenly seasoned, then divide into 4 equal portions and shape into flat patties.
03 - Lay out 4 large sheets of heavy-duty aluminum foil. Drizzle the center of each sheet with olive oil.
04 - Arrange potato slices on the oiled center of each foil sheet. Top with red onion, bell pepper, mushrooms, and cherry tomatoes. Season the vegetables with salt and pepper.
05 - Place one seasoned beef patty on top of each vegetable pile.
06 - Drizzle each patty with ketchup and yellow mustard.
07 - Fold the foil tightly around the contents to form fully sealed packets, ensuring no gaps for steam to escape.
08 - Place the sealed packets directly on hot coals or grill grates. Cook for 25 to 30 minutes, flipping once halfway through, until the potatoes are tender and the beef is cooked through.
09 - Carefully open each packet, watching for hot steam. Place a slice of cheddar cheese over each patty and reseal the packets for 1 to 2 minutes to allow the cheese to melt.
10 - Serve hot directly from the foil packets or transfer to hamburger buns with additional condiments as desired.