Combine ground beef, Worcestershire sauce and seasoning in a bowl. Mix well and shape into 6 evenly-sized patties.
Divide potatoes and carrots between 6 large pieces of lightly oiled heavy-duty aluminum foil. Season with salt, pepper, dried parsley and garlic powder.
Place hamburger patties on vegetables, then top with sliced onions and mushrooms. Season with more salt/pepper/parsley/garlic. Generously drizzle with olive oil, then seal foil packets.
Grill packets over medium heat, OR cook on hot campfire coals, 15 to 20 minutes per side. Alternatively, bake packets on a baking sheet at 375°F for 45-60 minutes, or until beef patties are done.
Video
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Notes
The hamburger patties can turn out dry if you overcook these foil packets. I kept the main recipe as simple as possible with minimum ingredients. But if you're very concerned about too-dry meat, you can top each patty with a slice of butter OR with 1-2 tablespoons condensed cream of chicken soup before sealing the foil packets.