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Portobello Burgers with Romesco Sauce
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5 from 11 votes

Portobello Romesco Burgers

The ultimate Portobello Burger recipe topped with provolone cheese, caramelized red onion, and a bright, tangy romesco sauce.
Prep Time30 minutes
Cook Time30 minutes
Total Time1 hour
Course: Main Course
Cuisine: American
Diet: Vegetarian
Servings: 4 burgers
Author: Jamie Vespa MS, RD

Equipment

  • Large skillet
  • Food processor
  • 9x13-inch baking pan

Ingredients

Portobello Burgers

  • 4 large portobello mushroom caps wiped cleaned and stems removed
  • 1/3 cup balsamic vinegar
  • 3 tbsp. extra-virgin olive oil
  • 1 Tbsp. Italian seasoning
  • 1/2 tsp. garlic powder
  • 1/2 tsp. each kosher salt and black pepper
  • 1 medium red onion, peeled and thinly sliced
  • 4 slices provolone cheese (or sliced cheese of choice)
  • 4 buns of choice, toasted
  • Microgreens or fresh arugula for garnish
  • Hummus or mayonnaise for topping

Romesco Sauce

  • 1 (12-oz.) jar roasted red peppers, drained
  • 1/3 cup sliced almonds (sub pine nuts or chopped walnuts)
  • 1/4 cup oil-packed sun-dried tomatoes, drained
  • 2 Tbsp. extra virgin olive oil
  • 1 Tbsp. red wine vinegar
  • 1 clove garlic
  • 1/2 tsp. smoked paprika
  • 1/2 tsp. each kosher salt and black pepper

Instructions

  • Marinate Mushrooms:
    Place mushroom caps in a 9x13-inch baking dish. In a medium bowl, combine 3 Tbsp. olive oil, balsamic vinegar, Italian seasoning, garlic powder, salt, and pepper; mix to combine.
    Pour marinade over mushrooms and use a pastry brush to brush on both sides, gently flipping mushrooms each time, and ending in stem-side-up position. Let sit, uncovered, at room temperature for at least 30 minutes (or up to 2 hours).
  • Prepare Romesco Sauce:
    Combine all romesco sauce ingredients in a blender or food processor. Blend until mostly smooth (a few chunks are fine). Set aside. 
  • Saute Red Onion:
    Heat 1 to 2 Tbsp. olive oil in a large skillet over medium heat. Once hot, add sliced onion and a pinch of salt. Sauté, stirring occasionally, until soft and slightly crisp around the edges, about 8 to 10 minutes. Transfer to a bowl.
  • Cook Mushrooms:
    Return the skillet to medium heat. Once hot, add portobello mushrooms and sauté for about 4 to 5 minutes minutes on each side, or until the mushrooms are deep golden brown on the edges and softened/reduced in size. While cooking, brush with any leftover marinade.
    Top each mushroom with a slice of cheese and place lid on pan. Cook for 1 additional minute, or until cheese is melted. 
  • Assemble Burgers:
    Lightly toast each half of bun. Spoon a generous portion of romesco sauce on the bottom bun and a swipe of hummus or mayonnaise on top bun. Stack bottom bun with one portobello mushroom, caramelized onions, and arugula or microgreens. Finish with top bun and enjoy immediately.

Notes

*Nutrition facts include portobello mushroom, bun, cheese, and romesco sauce.

Nutrition

Serving: 1burger | Calories: 439kcal | Carbohydrates: 42g | Protein: 16g | Fat: 23g | Saturated Fat: 4g | Sodium: 970mg | Fiber: 4.5g | Sugar: 10g