01 - Preheat your campfire, grill, or oven to medium-high heat (about 400°F).
02 - In a mixing bowl, combine the ground beef with garlic powder, onion powder, smoked paprika, salt, and pepper. Mix just until evenly incorporated, being careful not to overwork the meat.
03 - Divide the seasoned beef mixture into 4 equal portions.
04 - Tear 4 large sheets of heavy-duty aluminum foil (about 12 inches per side) and brush the centers lightly with olive oil to prevent sticking.
05 - Arrange potato slices in the center of each foil sheet, then layer onion, bell pepper, and mushrooms on top. Season the vegetables lightly with salt and pepper.
06 - Flatten each portion of seasoned beef into a patty and place one on top of the vegetables in each packet.
07 - Drizzle ½ tablespoon ketchup and a small amount of mustard over each patty.
08 - Fold the foil up and over to form tightly sealed packets, ensuring all edges are crimped closed to prevent leaks during cooking.
09 - Place the sealed packets on the campfire grate, grill, or in the oven. Cook for 20 to 25 minutes, flipping once halfway through, until the beef is cooked through and the vegetables are tender.
10 - Carefully open each packet, watching for hot steam. Place a slice of cheddar cheese on each patty, then reseal the packets for 2 more minutes to allow the cheese to melt.
11 - Serve directly from the packets or transfer to plates. Garnish with sliced pickles, chopped lettuce, tomato slices, and additional condiments as desired.