Open-Faced Cheeseburgers with Mushrooms and Onions

Prep Time:
10 mins
Total Time:
25 mins

Fontina is especially good on this burger. When heated, its texture becomes remarkably creamy and luscious.


  • 2 tablespoons olive oil

  • 10 ounces white mushrooms, trimmed and thinly sliced

  • Coarse salt and ground pepper

  • 1 medium red onion, halved and thinly sliced

  • 1 teaspoon red-wine vinegar

  • 1 pound ground beef chuck

  • 1 plum tomato, cored and cut lengthwise into 4 slices

  • 2 ounces Fontina cheese, cut into 4 slices

  • 4 slices sourdough bread (1 inch thick), toasted


  1. In a large skillet, heat 1 tablespoon oil over medium-high. Add mushrooms; season with salt and pepper. Cook, stirring occasionally, until mushrooms release their liquid and start to brown, 5 to 7 minutes; transfer to a bowl (reserve skillet).

  2. Add onion and remaining tablespoon oil to skillet; season with salt and pepper. Cook, stirring occasionally, until onion starts to brown, 5 to 7 minutes (if bottom of skillet becomes too dry, add a little water and scrape up browned bits). Return mushrooms to skillet; stir in vinegar and set aside.

  3. Heat broiler, with rack set 4 inches from heat. Gently form meat into 4 3/4-inch-thick patties; season with salt and pepper. Place on a rimmed baking sheet, and broil 3 minutes.

  4. Remove baking sheet; top burgers with tomato and cheese slices. Broil until cheese is melted and burgers are medium-rare, 1 to 2 minutes more. Serve burgers on toasted bread, with sauteed mushrooms and onion alongside.

Cook's Notes

If you prefer burgers that are done medium instead of medium-rare, broil the patties for 1 to 2 minutes longer before topping them with tomatoes and cheese.

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