01 - Build your campfire and let it establish hot coals, or preheat a grill to medium-high heat (375–400°F).
02 - In a large bowl, combine the ground beef with salt, pepper, garlic powder, and smoked paprika. Mix gently until evenly seasoned, then divide into 4 equal portions. Shape each into a flat, even patty about ½ inch thick.
03 - Tear 4 large sheets of heavy-duty aluminum foil, approximately 18 inches each. Lightly drizzle the center of each sheet with olive oil to prevent sticking.
04 - Arrange potato slices as the base layer on each foil sheet. Top with red onion, bell pepper, mushrooms, and cherry tomatoes if using. Season the vegetable layers with salt and pepper.
05 - Place one seasoned beef patty on top of each vegetable pile. Drizzle each patty lightly with ketchup and yellow mustard.
06 - Fold the foil tightly around the contents, crimping the edges firmly to create fully sealed packets that trap steam and juices inside.
07 - Place the sealed packets directly on hot coals or grill grates. Cook for 25–30 minutes, flipping once halfway through, until the potatoes are fork-tender and the beef is cooked through (internal temperature of 160°F).
08 - Carefully open each packet, watching for hot steam. Lay one slice of cheddar cheese over each patty and reseal the foil. Let rest for 1–2 minutes until the cheese melts.
09 - Serve hot directly from the foil packets, or slide the contents onto hamburger buns. Offer extra ketchup, mustard, and mayonnaise on the side if desired.