Portobello Mushroom Quesadillas with Caramelized Onions

Portobello Mushroom QuesadillasThis Portobello Mushroom Quesadilla with Caramelized Onions recipe is Gr8 for parties!

I caramelize the onions the day before, then prepare, arrange and pre-cook the quesadillas before the guests arrive. It’s easy to then reheat them. Then just cut them and lay them out on a platter with the chopped arugula sprinkled over the top. Your guests will be impressed!

Great as an appetizer or a main course.

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Portobello Mushroom Quesadillas

Recipe adapted by Shutterbean.

Portobello Mushroom Quesadillas with Caramelized Onions

Servings: 16 - 32 pieces

Adapted from Shutterbean.

Author Jurga


  • 3 Tablespoons olive oil, divided
  • 2 onions, thinly sliced
  • 1 Tablespoon dark brown sugar
  • 1/3 cup balsamic vinegar
  • 1 Tablespoon salted butter
  • 3 large cloves garlic, finely chopped
  • 4 portobello or other large flat mushrooms, thinly sliced
  • 1/2 teaspoon dried thyme leaves
  • 8 flour tortillas
  • 1 2/3 -2 cups shredded fontina or gruyère cheese
  • 1 handful baby arugula, roughly chopped
  • sour cream for garnish


  1. Heat 1 1/2 Tablespoons of the olive oil in a medium skillet, over low heat.
  2. Add the onion and cook until soft and translucent, about 10 minutes.

  3. Add the sugar and vinegar and cook until onion is caramelized and liquid has mostly evaporated.
  4. Transfer the onion mixture to a bowl and set aside.
  5. In the same skillet, add the remaining 1 1/2 Tablespoons of oil and butter.
  6. Add the mushrooms and sauté until mushrooms start to release juices.
  7. Add the garlic and thyme and cook mixture until mushrooms have completely softened.
  8. Season with salt and pepper.
  9. Remove pan from the heat and set aside.
  10. Heat a large pan or griddle over medium-high heat.
  11. One at a time, lightly toast all the tortillas on one side for a minute and set aside.
  12. Align 5 tortillas side by side toasted side up.
  13. Top each tortilla with cheese, onion, mushrooms, arugula, finishing with more of the cheese.
  14. Top each filled tortilla with the remaining tortilla, toasted side down.
  15. Add a little olive oil to pan or griddle and cook each side for 3 to 4 minutes per side, or until cheese is melted.

  16. Cut tortillas into quarters (or eights for smaller pieces) and sprinkle chopped arugula on top.
  17. Serve with a dollop of sour cream.

Recipe Notes

Gr8 Do Ahead Tip:
  • The onions can be caramelized the day before and refrigerated, covered.
  • Assemble the quesadillas right before guests arrive, then reheat them in a skillet (start at Step 12) when it’s time to serve.

Portobello Mushroom Quesadillas

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