Mushroom Swiss Burger Recipe

Mix and form patties

Place the ground beef in a bowl. Add kosher salt, black pepper, Worcestershire sauce, and garlic powder. Gently mix with your hands or a fork until just combined — avoid overworking. Divide the meat into four equal portions (about 4 oz each) and form into patties about 3/4" thick, making a shallow dimple in the center of each patty with your thumb to prevent puffing.

Cook patties

Preheat a cast-iron skillet or heavy-bottomed pan over medium-high heat until hot (about 2–3 minutes). Lightly oil the pan or brush patties with a little oil. Cook patties 3–4 minutes on the first side without moving them, until a good crust forms. Flip and cook 2–3 minutes on the second side for medium doneness. In the final minute of cooking, place one slice of Swiss cheese on each patty and cover the pan briefly (30–60 seconds) to melt the cheese. Remove patties to a plate and tent with foil to rest for 3 minutes.

Sauté mushrooms and onions

While the patties rest or before cooking burgers, heat a skillet over medium heat. Add butter and olive oil. When butter foams, add sliced mushrooms and sauté, stirring occasionally, until they begin to brown, about 5–6 minutes. Add the thinly sliced onion and continue to cook another 3–4 minutes until onions are softened and mushrooms are deeply golden.

Season and finish

Stir in fresh thyme leaves, soy sauce, salt, and black pepper. Cook another 30–60 seconds to allow flavors to meld. Taste and adjust seasoning. Remove from heat and keep warm until assembly.

Toast buns and make sauce

Mix the mayonnaise and Dijon mustard in a small bowl. Butter the cut sides of the buns with the reserved unsalted butter. Place buns cut-side down in a clean skillet over medium heat and toast until golden, about 1–2 minutes. Remove from heat.

Assemble burgers

Spread a tablespoon or so of the mayo-Dijon sauce on the bottom bun. Place a lettuce leaf and a tomato slice on the bottom bun. Put the Swiss-topped burger patty on top of the tomato. Spoon a generous portion of the warm mushroom-onion mixture over the melted Swiss cheese. Add a few thin red onion slices if desired. Cap with the top bun and serve immediately.