Portobello Burgers

This grilled portobello mushroom burger is topped with grilled onions, roasted red pepper and a tangy avocado chimichurri for the perfect bite! It’s a delicious plant-based idea for cookouts for all the vegetarians out there, even the meat eaters will love it!

Why You’ll Love These Portobello Burgers

This veggie-packed burger will be a new go-to recipe for summer cookouts and Meatless Mondays.

• Great for the summer. Burgers are a staple for any summer cookout. Everyone loves them!
• Veggie-friendly. This portobello mushroom burger with chimichurri is perfect for vegetarians and meat-lovers.
• Perfect for meal preps. Grill the veggies in advance and assemble your burgers throughout the week for a quick dinner.
• Versatile. Add bacon, creamy aioli, or swap the bread for focaccia if you feel like it.

Recipe Ingredients

Homemade chimichurri brightens things up and adds lots of natural creaminess. Scroll to the recipe card at the bottom of the post for exact amounts.

• Portobellos – Avoid ones that have a sticky skin because it means they’re no longer fresh.
• Olive oil – Feel free to use avocado or coconut oil.
• Ciabatta buns – If they’re slightly stale, sprinkle with 1/2 teaspoon water and microwave them in 10-second increments until warm before toasting them.
• Red bell pepper – You can use any color of bell pepper.
• Red onion – White and yellow onion works too.
• Spinach – Go for a salad mix, chopped kale, or arugula if you prefer.
• Salt – Kosher salt is best.

For the Avocado Chimichurri

• Avocado – Chunky guacamole is a great swap.
• Fresh cilantro – Remove any yellow or brown leaves and stems to prevent bitterness.
• Garlic – Fresh garlic or garlic paste are best. Don’t use garlic powder because it can make the mixture grainy.
• Lime juice – Lemon juice works too.
• Red wine vinegar – Apple cider vinegar is the only possible swap.
• Red pepper flakes – Cayenne pepper can be used instead.
• Salt and pepper – I prefer kosher salt and freshly-cracked black pepper.

How To Make A Portobello Mushroom Burger

They’re just like making your favorite grilled burgers but without any meat. Scroll to the bottom of the post for the full recipe card.

• Prep the mushrooms. Preheat the grill to medium-high heat (375-400 F). Use a spoon to scoop out the sides of the portobellos and remove the stem. Season the mushrooms and red peppers with olive oil and salt.
• Make the chimichurri. Use a fork to mash all of the chimichurri ingredients in a medium-sized bowl until well combined and smooth.

• Grill them. Grease the grill grates with cooking spray. Add the portobellos, red pepper, and onion. Grill the mushrooms for 4-5 minutes per side, the pepper for 5-6 minutes per side, and the onions for 3-4 minutes per side. Remove them from the heat and set them aside.
• Toast the bread. Add the ciabattas to the side of the grill for 2-3 minutes, until slightly toasted.

• Assemble the burgers. Use a knife to slice the grilled pepper. Spread 2 tablespoons chimichurri on each ciabatta slice. Top 2 of the slices with 1/2 cup spinach, 1 portobello burger, red pepper, and red onions. Place the other bread slices on top and enjoy!

Tips & Variations

It’s hard for portobello mushroom burgers to be boring when you can switch them up with smokey bacon, jalapeño poppers, and chipotle mayo.

• More protein. Add a layer of sliced tofu or a plant-based patty for a heartier bite.
• Use leftovers. Chop up leftover Bacon Wrapped Stuffed Jalapeños or Cheesy Bacon Stuffed Peppers and add them to the burger to reduce food waste.
• Change the bread. Use regular hamburger buns, focaccia, brioche, or sourdough to prepare these burgers if that’s what you’ve got on hand.
• Add crunch. Cook 2-3 bacon strips until crispy. Chop them up and add them to the burger for extra texture.
• Go for store-bought. Reduce prep time by skipping the homemade chimichurri for a store-bought one and you can mash in the avocado.
• Swap the spread. If you don’t want to add chimichurri, spread the bread with chipotle mayo, Sriracha mayo, cilantro lime crema, or Roasted Garlic Aioli.

What To Serve With Portobello Burgers

This portobello mushroom burger is an easy lunch with more veggie sides. Try it with my Corn on the Cob, Cucumber Feta Salad, or Simple Arugula Salad. For classic potato options, go for my Sweet Potato Fries, Garlic Parmesan Fries, or Smashed Potatoes. My Sweet Potatoes with Cilantro Lime Crema and Stuffed Sweet Potatoes are great too.

Proper Storage

I only recommend storing the portobello steaks and toppings, not the bread because it’ll soften.

• Fridge: Store everything in separate airtight containers for up to 4 days. Discard the portobellos immediately if they taste sour.
• To reheat it: Microwave the portobellos in 15-second increments until warm. You can also heat them in a pan over medium-high heat for 2-3 minutes per side.

More Burger Recipes To Try

• Zesty Chimichurri Burgers
• Paleo Chipotle Turkey Burgers with Guacamole
• Mushroom Burger with Horseradish Aioli
• BBQ Chicken Burgers with Caramelized Onions

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