01 -
Heat olive oil in a large skillet over medium heat. Add sliced onions and cook for 10 to 12 minutes, stirring regularly, until deeply golden and caramelized.
02 -
Add minced garlic to the onions and cook for 1 to 2 minutes until fragrant.
03 -
Add ground beef to the skillet. Cook, breaking it apart with a spatula, until fully browned.
04 -
Drain any excess fat. Stir in Worcestershire sauce, soy sauce, dried thyme, salt, and pepper. Let the mixture simmer for 5 minutes to develop flavor.
05 -
While the beef mixture simmers, toast hamburger buns until golden.
06 -
Spoon the beef mixture onto the bottom half of each toasted bun. Top with shredded Swiss cheese and place the remaining bun halves on top.
07 -
Garnish with chopped fresh parsley before serving, if desired.