Vegan Caramelized Onion and Mushroom Panini With Sun-Dried Tomato Mayonnaise Recipe

J. Kenji Lopez-Alt

A hearty vegan sandwich with a balance of sweet caramelized onions, savory mushrooms, and a tangy sun-dried tomato mayonnaise.

Recipe Facts

Active: 35 mins
Total: 45 mins
Serves: 2 servings

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  • 2 tablespoons olive oil, divided

  • 2 medium onions, thinly sliced (about 3 cups)

  • Kosher salt and freshly ground black pepper

  • 1 pound button, shiitake, cremini, or portabello mushrooms, trimmed and thinly sliced

  • 2 medium cloves garlic, minced

  • 1 teaspoon soy sauce

  • 1 tablespoon fresh lemon juice

  • 1/4 cup homemade or store-bought vegan mayonnaise

  • 1/3 cup oil-packed sun-dried tomatoes

  • 2 small loaves ciabatta or other hearty rolls, split in half


  1. Heat 1 tablespoon oil in a large saucepan over medium heat until shimmering. Add onions, season with salt and pepper, and cook, stirring frequently, until lightly browned and a pale brown patina builds up on the bottom of the pan, about 10 minutes. Add 1 tablespoon water and scrape up browned bits. Repeat, cooking, adding water, and scraping up bits until onions are soft and very sweet, about 30 minutes total. Transfer to a bowl and set aside.

  2. While onions cook, heat remaining oil in a large skillet over high heat until shimmering. Add sliced mushrooms, season lightly with salt and pepper, and cook, stirring occasionally, until mushrooms have released all their liquid, the liquid has evaporated, and the mushrooms have deeply browned, about 15 minutes. Add half of garlic and cook, stirring constantly, until fragrant, about 30 seconds. Add soy sauce and half of lemon juice and stir to combine. Season to taste with salt and pepper. Transfer to a bowl and set aside.

  3. Combine mayonnaise, remaining lemon juice, tomatoes, and garlic in a food processor. Process until a rough purée is formed, about 30 seconds, scraping down sides as necessary.

  4. Preheat a panini press. Spread both sides of rolls with sun-dried tomato mayonnaise, top bottom bun with onions and mushrooms, close sandwiches, place in press, close gently, and cook for 5 minutes. Press more firmly to compress sandwiches and continue cooking until crisp and fully heated through, about 5 minutes longer. Serve immediately.

Special equipment

Panini press, food processor

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Nutrition Facts (per serving)
679 Calories
34g Fat
85g Carbs
16g Protein
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Nutrition Facts
Servings: 2
Amount per serving
Calories 679
% Daily Value*
Total Fat 34g 43%
Saturated Fat 5g 25%
Cholesterol 0mg 0%
Sodium 1522mg 66%
Total Carbohydrate 85g 31%
Dietary Fiber 12g 41%
Total Sugars 20g
Protein 16g
Vitamin C 31mg 156%
Calcium 180mg 14%
Iron 5mg 28%
Potassium 1397mg 30%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)