Portobello Mushrooms with Grilled Onions and Cheddar Cheese

Updated February 23, 2016
This image courtesy of Joseph DeLeo

Grilled whole portobello mushrooms are a good vegetarian substitute for hamburger, especially when topped with grilled red onions and cheddar cheese. Chipotle ketchup provides acidity and spice, but you may substitute mayonnaise, with maybe a teaspoon of chopped parsley or basil, if you prefer a milder sauce. At Bread Alone, we make our own deliciously crusty Kaiser rolls. Seek out rolls of similar substance, and avoid commercial hamburger buns at all cost.

Makes2 sandwiches



Total Timeunder 30 minutes

Recipe Coursemain course

Dietary Considerationegg-free, halal, kosher, peanut free, soy free, tree nut free, vegetarian

Equipmentpanini press


Taste and Texturechewy, sharp, umami

Type of Dishgrilled sandwich, sandwich


  • 2 large portobello mushrooms, stemmed and wiped clean
  • Two ½-inch-thick slices red onion
  • 2 tablespoons olive oil
  • Salt and freshly ground black pepper to taste
  • 2 round Italian rolls
  • ¼ cup Chipotle Ketchup
  • 3 ounces cheddar cheese, thinly sliced


Heat a panini or sandwich press according to the manufacturer’s instructions.

Brush the mushrooms and onions with olive oil and sprinkle with salt and pepper. Place them on the press, pull the top down, and cook until softened and browned, 4 to 6 minutes. Transfer to a plate and let cool slightly.

Cut the rolls in half with a sharp serrated knife. Spread some chipotle ketchup on the bottom half of each roll. Place a mushroom on each bottom half. Top with a slice of grilled onion. Cover the onion with cheese. Top the sandwiches with the top halves of the rolls.

Put the sandwiches on the press, pull the top down, and cook until they are browned and crisp and the cheese is melted, 5 to 7 minutes, depending on how hot your machine is. Carefully remove from the press and serve immediately.


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