The ultimate Portobello Burger recipe topped with provolone cheese, caramelized red onion, and a bright, tangy romesco sauce. The heartiest meatless burgers that both vegetarians and meat eaters will love.
Here’s the lowdown on these savory portobello burgers. They are:
- Infused with a deeply savory balsamic marinade.
- Seared in a skillet (no grilling required!)
- Blanketed with melty provolone cheese.
- Piled inside a fluffy brioche bun.
- Lathered in romesco sauce.
The biggest bonus of these burgs is that they appeal to both omnivores and veg heads. It’s impossible to resist their meaty texture and saucy attributes. In fact, I fed these to some of the biggest meat lovers I know with raving reactions.
Right at the intersection at hearty and healthy, and delectably messy — as a burger should be.
How to Make Portobello Burgers
The key to mega mushroom success is to enhance their earthy flavor with a savory, spice-infused marinade that plays up the portobellos’ umami factor.
- For the max flavor impact, I recommend marinating the portobello mushrooms for at least 30 minutes or up to two hours. Use the time while you wait to prep any toppings or sides.
The savory profile of the marinade plays particularly well with the brightness of the romesco sauce. And with whichever cool and crunchy garnishes you decide to also crown these glorious burgs with.
- Portobello Mushrooms: Portobello mushrooms have a certain “meaty” factor to them that reigns supreme in the veggie kingdom. You’ll want to remove and discard the stems, and wipe the caps clean with a moist paper towel before cooking.
- Balsamic Vinegar: Delightfully tangy, balsamic adds a certain “oomph” to the marinade.
- Spices: Good ol’ Italian seasoning gives the shrooms an herbaceous backbone. You’ll also need a little smoked paprika for the romesco sauce.
- Cheese: I love topping these burgers with provolone, however any sliced cheese works! You can also omit the cheese entirely if making vegan/dairy-free.
- Roasted Red Peppers: You need 1 (12-oz.) jar of roasted red peppers for the sauce. Alternatively, you can roast your own bell peppers, however you can’t beat the convenience of jarred.
- Almonds: Either raw or roasted almonds will work. Alternatively, you can use pine nuts or walnuts.
- Garlic: 1 or 2 cloves of raw garlic adds an aromatic foundation to the sauce.
- Vinegar: The acidity of red wine vinegar really livens up the romesco sauce. Alternatively, you can use sherry vinegar or lemon juice.
- Sun-Dried Tomatoes: Most classic romesco sauces call for plum tomatoes or tomato paste, however the extra umami factor of sun-dried.
- Olive Oil: Make sure you have plenty of olive oil on hand for the mushroom marinade and romesco sauce.
Step 1: Marinate the Mushrooms
Place mushroom caps in a 9×13-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 each time, and ending with stem-side-up position. Let sit, uncovered, at room temperature for at least 30 minutes (or up to 2 hours).
Step 2: Blend Romesco Sauce
Meanwhile, prepare romesco sauce by combining all ingredients in a blender or food processor. Blend until mostly creamy (a few chunks are fine). Set aside.
Step 3: Sauté Red Onion
Step 4: Cook Portobello 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 for extra flavor.
Top each mushroom with a slice of cheese and place lid on pan. Cook for 1 additional minute, or until cheese is melted.
Step 5: Assemble Portobello 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, ending with top bun.
Portobello Burger Toppings:
Use this portobello burger recipe more as a template to create a build-your-own masterpiece.
- Fresh Veggies: I love adding a fresh, crunchy component like microgreens or arugula, which have a little spice to their bite.
- Caramelized Onions: Whether you’re caramelizing a red or yellow onion, they make the ultimate burger topping.
- Fried Egg: A runny fried egg just hits different when you bite into a burger. This will give the portobello burgers a real steakhouse experience.
- Cheese: Go for a melty cheese like provolone or cheddar, or go fancy with a crumbled option like goat or blue cheese.
- Avocado: For creaminess and extra heart-healthy fats, mashed or sliced avocado is always a great option.
What to Serve with Portobello Burgers:
A few of my favorite sides:
- Cobb Salad: For the real gourmet burger experience, serve this Strawberry Cobb Salad with Fried Feta on the side.
- Smashed Potatoes: Why choose fries when you could enjoy these Paprika-Parmesan Smashed Potatoes with Aioli instead?
- Potato Salad: The Mediterranean flavors of this Pesto Potato Salad will bode particularly well with the burgers.
- Sautéed Veggies: Keep it light + low carb with this Perfect Sautéed Broccoli.
More Portobello Mushroom Recipes to Try
Portobello Romesco Burgers
- Large skillet
- Food processor
- 9x13-inch baking pan
- 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
- 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
- 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.