Savor the rich, earthy flavors of these Portobello Mushroom Burgers, elevated to gourmet status with a luscious layer of homemade pesto aioli and sweet, caramelized onions. This plant-based delight is a mouthwatering combo, making them a big hit for both vegetarians and meat eaters alike!
Save This Recipe! 💌
We'll email this post to you, so you can come back to it later!
If you're looking for more veggie options to serve a crowd, or just to incorporate into your own diet, you will be blown away by these flavor-packed portobello burgers! These meatless burgers are absolutely bursting with so much flavor, and are an excellent vegetarian option for BBQs and get-togethers. They can easily be made vegan as well!
Love mushrooms? You may also like these caramelized onions and mushrooms, this creamy keto mushroom sauce, or this lemon butter cauliflower and mushroom recipe.
Jump to:
❤️Why we love this recipe
- Flavor explosion. The combo of pesto aioli, caramelized onions, and a well-marinated Portobello cap packs a serious flavor punch. Add melty cheese, toasted buns, peppery arugula, and in-season tomatoes for an incredible bite packed with earthy flavor.
- Vegetarian recipe. This recipe provides a hearty and satisfying option for vegetarians, without compromising on taste or texture. This is also a great option to make for vegans with just a few considerations.
- Veggie packed & customizable for different diet types. This burger is full of flavorful veggies, making it wholesome and super tasty too! If you're a fan of mushrooms, whether you're a meat eater or not, this vegetarian burger option is the real deal, with an incredible meaty texture and savory flavor. Make this for meatless Mondays and impress everyone!
- Gourmet while approachable. The ingredients may sound fancy, but the cooking steps are straightforward enough for cooks of all levels. The simple steps are made foolproof with our step-by-step instructions and process images.
🍄Ingredients
Here are the ingredients we used for this recipe. You can find more information for substitutions below.
- Large Portobello mushroom caps - Make sure to grab the large mushrooms in the store, that are roughly the size of a burger bun!
- Balsamic vinegar
- Vegan Worcestershire sauce (to keep this dish vegetarian)
- Kosher salt and black pepper
- Italian seasoning
- Oregano
- Smoked paprika
- Olive oil
- Fresh garlic
- Onions - Choose yellow or Vidalia onions that have a nice and sweet flavor.
- White wine - Choose a non-oaky white wine like Pinot Grigio or Sauvignon Blanc.
- Maple syrup
- Cheese slices - Choose anything you like here. Mozzarella and smoked gouda are our favorite.
- Burger buns
- Pesto aioli - We make our pesto aioli a day or two in advance usually and store it in the fridge.
- Basil
- Arugula
- Tomato - Optional. We like to choose a nice ripe heirloom tomato when they are in season and slice them really thin.
Visit the recipe card for the full quantities and nutritional information.
✨Substitutions
Here are a few suggestions on additional flavors to try, or simple variations to this recipe.
- Swap the fresh garlic. Freshly minced garlic is always the best, but you can also use garlic powder.
- No Worcestershire sauce. If you can't find vegan Worcestershire sauce or don't have any on hand, swap in some soy sauce or tamari.
- Herb swap. If you don't have Italian seasoning, you can use a mix of oregano, thyme, rosemary, and basil.
- Spicy. Add in cayenne pepper, chili powder, and a little red pepper flakes to the seasoning blend for a kick of heat.
- Swap the onions. Use red onions for a slightly different flavor profile.
- Use a different sweetener. You can use any sweetener you prefer for this recipe. Honey also makes a great choice! It's a good idea to add a bit of sweetness to the onions to give them a really deep flavor.
- Swap the white wine. Don't want to cook with wine? No problem, just add some veggie stock.
✨Variations
- Vegan burgers. This recipe is easily made vegan by making a vegan version of our pesto aioli with vegan mayo, and a vegan pesto. Try making our walnut pesto recipe, and omit the parmesan cheese, and swap in a teaspoon or two of nutritional yeast for that cheesy flavor. Also, be sure to use vegan-friendly hamburger buns, and use some vegan cheese slices. Follow Your Heart makes some really amazing vegan mayo and cheese that melts really well with great flavor!
- Gluten free. Use gluten-free buns, and be sure your Worcestershire sauce is gluten-free. You can also use tamari for a gluten-free option.
- Low carb. For a low carb option, use your favorite low carb buns, or make it a lettuce wrap. You can also swap the maple syrup for your favorite low sugar option if looking to lower the carbs even further. We recommend this sugar free maple syrup.
🔪Prep work
- The pesto aioli can be made a day or two in advance and stored in the fridge in an airtight container.
- Clean off the portobello mushrooms with a damp paper towel to rub off any dirt.
- Mince garlic.
- Thinly slice onions.
- Cut tomatoes into thin slices.
- Wash and dry arugula.
- Measure out all remaining ingredients.
📋Instructions
In a saucepan or large skillet over medium heat, add olive oil, onions, and a pinch of salt. (Image 1)
Cook for about 5 minutes, stirring occasionally, until the onions have started to soften. Then, add in the white wine, Worcestershire sauce, maple syrup, and balsamic vinegar to deglaze the pan. Stir to combine, and scrape the bottom of the pan to scrape up any browned bits. (Image 2)
Increase to medium-high heat. Stir every 5 minutes or so until there is no excess liquid in the pan. (Image 3)
The onions should have nice browned edges and become golden brown. This will take roughly 30 - 40 minutes. Add more white wine if the pan begins to dry out too much. Cook until desired consistency is reached. Adjust the seasonings to taste, then set aside. (Image 4)
Now for the flavorful marinade for the mushrooms. While the onions are cooking, combine olive oil, balsamic vinegar, vegan Worcestershire sauce, minced garlic, Italian seasoning, smoked paprika, oregano, black pepper, and some kosher salt in a large baking dish. Whisk to combine. (Image 5)
Place the portobello caps cap side down into the marinade, and let them sit for 10 minutes or so. (Image 6)
Flip the mushrooms cap side up, then let them sit for another 10 minutes or so. (Image 7) During the last 10 minutes of marinating, begin preheating a grill pan or skillet over medium heat. You can also use an outdoor grill if you'd like!
✨Pro Tip: You can marinate the mushroom caps even longer if you like, up to overnight!
Once the mushrooms have finished marinating, spray the mushroom cap tops with cooking spray, then place them on the hot grill, cap side down. Grill for about 3-5 minutes, or until nice grill marks form. (Image 8)
As soon as you flip the mushrooms, add a slice of cheese overtop, and grill for another 2-4 minutes until the cheese has melted. (Image 9) Set aside and cover to keep warm.
✨Pro Tip: Make sure to grease the grill grates or grill pan well if using so that the mushrooms don't stick to the pan.
*If desired, you can toast the burger buns while waiting for the mushrooms. Preheat a separate griddle or pan over medium heat. Brush both sides of the inside of the hamburger buns with some mayo, and place the mayonnaise side down onto the hot skillet pan. Cook until nice and golden brown, about 1-2 minutes, then remove from the pan.
Now, simply assemble the burgers with pesto aioli, some caramelized onions, the mushrooms, tomato slices, more pesto aioli, and caramelized onions, and finally, top with arugula. (Image 10)
Serve, and enjoy!
✨Tips & tricks
- Don't skip marinating the mushrooms. This infuses so much flavor into the mushrooms, and gives it an incredible savory flavor!
- Take your time caramelizing the onions. Caramelizing onions takes time, but it's worth it. You can't speed the process up, so just be patient, and you will be rewarded with incredible tasty morsels of onions!
- Toast the buns! This step is optional but yields an incredible result. The crispy buns create a great base to layer on all of the toppings, and the texture is really great.
Need supplies? Shop our Amazon store! Stock your pantry, and find all of our favorite kitchen tools! A Full Living LLC earns a small commission through purchases on our storefront to help support this site.
💭Frequently Asked Questions
Store leftover ingredients separately in airtight containers in the fridge. We don't recommend storing pre-made burgers fully assembled in the fridge. The aioli and caramelized onions should be good for up to a week, while the marinated mushrooms are best eaten within 2-3 days. Do not freeze.
Yes, you can make the pesto aioli a day or two in advance. You can also marinate the Portobello mushrooms overnight. The caramelized onions reheat really well, so feel free to make those up to 4 days in advance as well.
Side dish ideas
Not sure what to serve with these mushroom burgers? Here are a few suggestions!
- Air fryer zucchini
- Lemon garlic green beans
- Air fryer waffle fries
- Air fryer shishito peppers
- Arugula and spinach salad
More Recipes To Consider
Did you try this recipe? Make sure to leave a 5-star review below! 🌟 This helps other readers find our recipes and encourages them to try them. Also, be sure to leave a comment with your experience. Follow along, and tag @AFullLiving on Instagram with your photos!
📖 Recipe
Portobello Mushroom Burgers
Equipment
- spatula
- wooden spoon
Ingredients
Caramelized onions
- 2 tablespoons olive oil
- 2 medium sweet onions, thinly sliced
- 1 cup white wine (can substitute veggie stock or water, if using white, choose a non-oaky wine)
- 1 tablespoon balsamic vinegar
- 1 tablespoon vegan Worcestershire sauce
- 1 tablespoon maple syrup (optional and to taste)
- ½ teaspoon kosher salt (or to taste)
Marinated mushrooms
- ¼ cup balsamic vinegar
- ¼ cup olive oil
- 3 cloves garlic, minced
- 1 tablespoon vegan Worcestershire sauce
- 1 teaspoon kosher salt
- 1 teaspoon Italian seasoning
- 1 teaspoon oregano
- ½ teaspoon smoked paprika
- ½ teaspoon black pepper
- 4 large Portobello mushroom caps (the size of a burger)
Burgers
- 4 slices cheese (your choice)
- 4 hamburger buns
- 4 tablespoons mayonnaisse (optional)
- 2 ounces arugula
- ½ large tomato, sliced
- 4 servings pesto aioli
Instructions
Caramelized onions
- In a saucepan or large skillet over medium heat, add 2 tablespoons of olive oil, the onions, and a pinch of salt. Cook for about 5 minutes, stirring occasionally, until the onions have started to soften. Then, add in 1 cup of white wine, 1 tablespoon Worcestershire sauce, 1 tablespoon of maple syrup, and 1 tablespoon of balsamic vinegar to deglaze the pan. Stir to combine, and scrape the bottom of the pan to scrape up any browned bits.
- Increase to medium-high heat. Stir every 5 minutes or so until there is no excess liquid in the pan. The onions should have nice browned edges and become golden brown. This will take roughly 30 - 40 minutes. Add more white wine if the pan begins to dry out too much. Cook until desired consistency is reached. Adjust the seasonings to taste, then set aside.
Marinated mushrooms
- While the onions are cooking, combine ¼ cup of olive oil, ¼ cup of balsamic vinegar, 1 tablespoon vegan Worcestershire sauce, 3 cloves of minced garlic, 1 teaspoon of kosher salt, 1 teaspoon of Italian seasoning, 1 teaspoon of oregano, ½ teaspoon of smoked paprika, and ½ teaspoon of black pepper, in a large baking dish. Whisk to combine.
- Place the portobello caps cap side down into the marinade, and let them sit for 10 minutes or so.
- Flip the mushrooms cap side up, then let them sit for another 10 minutes or so. During the last 10 minutes of marinating, begin preheating a grill pan or skillet over medium heat. You can also use an outdoor grill if you'd like!
Grilling the mushrooms
- Preheat a grill pan or skillet over medium heat, and grease the grates well to prevent sticking. Once the mushrooms have finished marinating, spray the mushroom cap tops with cooking spray, then place them on the hot griddle or pan, cap side down. Grill for about 3-5 minutes, or until nice grill marks form.
- As soon as you flip the mushrooms, add a slice of cheese overtop, and grill for another 2-4 minutes until the cheese has melted. Set aside and cover to keep warm.
Toast the buns (optional step)
- *If desired, you can toast the burger buns while waiting for the mushrooms. Preheat a separate griddle or pan over medium heat. Brush both sides of the inside of the hamburger buns with some mayo, about 1 tablespoon of mayo per bun, and place the mayonnaise side down onto the hot skillet pan. Cook until nice and golden brown, about 1-2 minutes, then remove from the pan.
Assembly
- Now, simply assemble the burgers with pesto aioli, some caramelized onions, the mushrooms, tomato slices, more pesto aioli, and more caramelized onions, and finally, top with arugula. Dig in!
- Store leftover ingredients separately in airtight containers in the fridge. We don't recommend storing pre-made burgers fully assembled in the fridge. The aioli and caramelized onions should be good for up to a week, while the marinated mushrooms are best eaten within 2-3 days. Do not freeze.
Save This Recipe! 💌
We'll email this post to you, so you can come back to it later!
Notes
- Vegan burgers. This recipe is easily made vegan by making a vegan version of our pesto aioli with vegan mayo, and a vegan pesto. Try making our walnut pesto recipe, and omit the parmesan cheese, and swap in a teaspoon or two of nutritional yeast for that cheesy flavor. Also, be sure to use vegan-friendly hamburger buns, and use some vegan cheese slices. Follow Your Heart makes some really amazing vegan mayo and cheese that melts really well with great flavor!
- Prepping ahead. You can make the pesto aioli a day or two in advance. You can also marinate the Portobello mushrooms overnight. The caramelized onions reheat really well, so feel free to make those up to 4 days in advance as well.
- Don't skip marinating the mushrooms. This infuses so much flavor into the mushrooms, and gives it an incredible savory flavor!
- Take your time caramelizing the onions. Caramelizing onions takes time, but it's worth it. You can't speed the process up, so just be patient, and you will be rewarded with incredible tasty morsels of onions!
- Toast the buns! This step is optional but yields an incredible result. The crispy buns create a great base to layer on all of the toppings, and the texture is really great.
Comments
No Comments