Now, let’s get cooking! Here’s how you can bring these flavors to life in your own kitchen:

1. Start by preparing the secret sauce. In a small bowl, combine mayonnaise, ketchup, Dijon mustard, pickle relish, and smoked paprika. Mix until smooth and set aside.
2. In a large skillet over medium heat, add olive oil and sliced onions. Cook, stirring occasionally, until the onions are caramelized, about 15 minutes. Remove from the skillet and set aside.
3. In a mixing bowl, combine ground beef, Worcestershire sauce, garlic powder, salt, and pepper. Form into four equal patties.
4. Using the same skillet, increase the heat to medium-high and cook the patties for about 4-5 minutes per side, or until they reach your desired level of doneness. Remove and let them rest.
5. Butter one side of each slice of rye bread. On the unbuttered side, spread a generous layer of secret sauce.
6. Assemble the sandwiches by placing a slice of Swiss cheese on the sauced side of the bread, followed by a beef patty, caramelized onions, another slice of cheese, and another slice of bread, buttered side out.
7. Return the skillet to medium heat and grill each sandwich for about 3-4 minutes per side, or until the bread is golden brown and the cheese is melted.
8. Slice and serve immediately, savoring each bite of the melty, flavorful goodness.