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Portobello Burgers

Portobello Burgers

with Avocado, Caramelized Onions, and Spicy Mayo

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Juicy portobellos are so hearty, they make the perfect vegetarian “burger”. Seared and finished with balsamic vinegar, these portobellos are served with caramelized onions, mashed avocado, and our favorite condiment: spicy mayo. A side salad rounds out this hearty summer meal.


Produced in a facility that processes eggs, milk, fish, peanuts, sesame, shellfish, soy, tree nuts, and wheat.

Total Time25 minutes
Cooking difficultyEasy
serving amount
Ingredientsarrow down iconarrow down icon
serving amount

1 jar



1 unit

Roma Tomato

1 unit

Yellow Onion

2 teaspoon

Hot Sauce

8 ounce

Portobello Mushrooms

2 tablespoon

Balsamic Vinegar

2 bun

Potato Buns

(ContainsEggs, Milk, Soy, Wheat)

1 unit


2 ounce


Not included in your delivery

2 teaspoon

Olive Oil


Kosher Salt



Nutrition Values/ per serving
Nutrition Valuesarrow down iconarrow down icon
/ per serving
Calories542 kcal
Energy (kJ)2268 kJ
Fat34 g
Saturated Fat4 g
Carbohydrate53 g
Sugar13 g
Dietary Fiber9 g
Protein10 g
Cholesterol0 mg
Sodium342 mg
Due to the different suppliers we purchase our products from, nutritional facts per meal can vary from the website to what is received in the delivered box, depending on your region.
Utensilsarrow down iconarrow down icon
Small Bowl
Large Pan
Instructionsarrow up iconarrow up icon
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Wash and dry all produce. Peel the onion, then slice end-to-end into thin rings. Separate the rings. Thinly slice the tomato into rounds. In a small bowl, combine the mayonnaise and as much hot sauce as you like.


Heat a drizzle of olive oil in a large pan over medium heat. Add the onions and cook, tossing for 4-5 minutes, until softened and slightly golden. Season with salt and pepper. Remove from the pan and set aside.


Heat the same pan over medium heat. Rub the Portobello caps on each side with olive oil and season with salt and pepper. Add them to the pan and cook for 4-5 minutes per side, until very soft. Add 1 ½ Tablespoons balsamic vinegar to the pan (reserving the rest for the salad) for another minute, until the vinegar reduces by half. After tossing the Portobellos in the balsamic glaze, remove from the pan and set aside.


Toast the buns: Split the buns. Clean out the same pan and heat over medium-high. Add the buns to the pan cut-side down and toast for 3-4 minutes, until golden brown.


Halve, pit, and scoop the avocado flesh into a small bowl; mash with a fork and season to taste with salt and pepper.


Finish and serve: In a medium bowl, toss the arugula with a drizzle of olive oil, the remaining balsamic vinegar, and pinch of salt and pepper. Spread the buns with the spicy mayo and top with the Portobello caps, tomato rounds, onions, and mashed avocado. Serve the arugula salad to the side and enjoy!