The Swiss Burger Recipe

Make the sauce

In a small bowl combine mayonnaise, Dijon mustard, ketchup, Worcestershire sauce, pickle relish, smoked paprika, and lemon juice. Whisk until smooth. Taste and adjust seasoning; set aside in refrigerator while you prepare other components.

Prepare garnishes: wash and dry lettuce leaves and slice tomato. Keep chilled until assembly.

Heat a skillet over medium-low heat. Add 1 tablespoon butter and 1 teaspoon olive oil. Add thinly sliced onion and 1/4 tsp salt, toss to coat.

Cook slowly, stirring every 3–5 minutes so onions brown evenly. After about 15 minutes, add 1/2 tsp brown sugar (optional) to accelerate caramelization and continue cooking another 8–12 minutes until deep golden and soft. Remove from heat and keep warm. Total time: ~25–30 minutes.

In a separate skillet over medium-high heat, add 1 tablespoon olive oil and 1 tablespoon butter. When butter foams, add the sliced mushrooms in a single layer. Do not overcrowd—cook in batches if necessary.

Let mushrooms sear undisturbed for 2–3 minutes, then stir. Add minced garlic, fresh thyme (if using), 1/2 tsp salt and 1/4 tsp pepper. Continue cooking 3–4 more minutes until mushrooms are golden and any liquid has evaporated. Remove from heat and keep warm.

Form beef into two even patties (about 8 oz each if making two burgers; if you prefer smaller patties, divide accordingly). Make a shallow dimple in the center of each patty with your thumb to prevent bulging. Season both sides with the 1 tsp salt and 1/2 tsp black pepper.

Preheat a grill or heavy skillet (cast iron) to medium-high. Brush the grates or skillet lightly with oil or spread softened butter on the top side of the buns for toasting.

Cook patties for about 3–4 minutes per side for medium (adjust time for desired doneness). Avoid pressing the patties while cooking. In the last 1–2 minutes of cooking, place 2 slices of Swiss cheese on each patty, cover the grill or skillet briefly to melt the cheese (about 1–2 minutes).

While patties rest for 2–3 minutes, toast buns cut-side down on the grill or skillet until lightly browned (about 30–60 seconds).

Assemble each burger: spread a generous tablespoon of special sauce on the bottom bun, add lettuce (if using) and tomato slice, place the Swiss-topped patty, spoon a heaping portion of sautéed mushrooms over the cheese, add a good portion of caramelized onions, top with additional sauce on the top bun if desired, and close the burger.

Serve immediately with your choice of sides.