Portobello Mushroom Burger

Savory grilled portobello mushrooms, onions, spinach, mayo, and sun-dried tomatoes are piled onto a fluffy bun to create a mouthwatering burger experience that happens to be vegetarian. You won’t even miss the meat!

Three mushroom burgers on a platter.
Lori Rice

Hello portobello mushroom burgers!

Why Portobello Mushroom Are the Best for Burgers

I grew up seeing these as a vegetarian option in restaurants and cafes. But here's the thing, for mushroom lovers (that would be me, you too?), portobellos are perfect for burgers, whether you are vegetarian or not.

The cap of this ginormous cremini mushroom is the perfect size and shape of a burger. The mushroom is meaty and juicy and umami-y.

How to Make Portobello Mushroom Burgers

Paint the caps with a little olive oil, put them on the grill for a few minutes on each side, and you have a perfect grilled mushroom to put between two burger buns.

In the following rendition, we've layered on grilled onions, some sautéed spinach, and sun-dried tomatoes, but it's just as good plain, with a little salt and pepper.

Three mushroom burgers on a platter.
Lori Rice

How to Select the Best Portobello Mushrooms at the Store

Look for mushroom caps that are brown, firm to the touch, and don't have any brown spots. If a portobello is tacky or slimy, do not choose it. For caps that all cook evenly, buy portobellos that are similar in thickness and diameter. For more information, see How to Buy and Store Mushrooms.

How to Clean Portobello Mushrooms

Follow these tips for cleaning portobello mushrooms.

  • If the mushrooms have stems, slice them off, taking care not to break the mushroom while doing so.
  • There is no need to remove the gills.
  • If the mushrooms are very dirty, wash them off in water. Pat dry with a paper towel.
  • If the mushrooms are slightly dirty or a little sticky/slimy, wipe them off with a damp paper towel. (If the mushrooms are very slimy, do not eat them.)
  • For more mushroom cleaning tips, see How to Clean and Prep Mushrooms for Cooking.

Other Methods for Cooking for Portobello Mushroom Burgers

If you don't have an outdoor grill, or don't feel like grilling outside, cook the portobellos indoors. Try one of these options.

  • An indoor electric grill, such as a George Foreman Grill
  • A cast iron grill pan on the stovetop
  • A cast iron skillet on the stovetop

The Best Toppings for Portobello Mushroom Burgers

  • Substitute a garlic and herb cheese spread for the mayonnaise.
  • Substitute aioli for the mayonnaise.
  • Substitute roasted red peppers in oil for the sun-dried tomatoes.
  • Add caramelized onions.
  • Add cheese like feta, mozzarella, or cheddar.

Can Portobello Burgers Be Made Ahead of Time?

These are best right off the grill, and they're so quick to make you don't save much time doing them in advance anyway.

More Vegetarian Burger Recipes to Try!

From the Editors Of Simply Recipes

Portobello Mushroom Burger

Prep Time 10 mins
Cook Time 20 mins
Total Time 30 mins
Servings 4 servings

Ingredients

  • Extra virgin olive oil
  • 8 ounces baby spinach
  • 4 portobello mushroom caps
  • 1 (8-ounce) jar sun-dried tomatoes in oil
  • 1 red onion, sliced into 1/4-inch rounds
  • Kosher salt
  • Mayonnaise
  • 4 hamburger buns

Method

  1. Prepare the grill:

    Heat the grill for high, direct heat.

  2. Wilt the spinach:

    While the grill is heating, if you wish, sauté the baby spinach in a tablespoon of olive oil and a sprinkle of salt in a large sauté pan on medium high heat, just until the spinach wilts, then remove to a plate.

    The gently wilted spinach will stay on the portobello mushroom burger better than raw spinach, which tends to fall off.

    Or, you can use raw baby spinach. Your choice.

    Sauteed greens in a skillet to make a portobello mushroom burger recipe.
    Lori Rice
  3. Clean the mushrooms and brush with oil:

    Wipe the mushrooms clean with a damp paper towel. If you are working with whole mushrooms, slice off the stems. (You can use for another purpose, chopped and sautéed or for making stock.)

    Paint the tops of the mushroom caps with some of the oil from the sun-dried tomatoes.

    Brushing off the top of a portobello mushroom to make a portobello mushroom burger.
    Lori Rice
    Oiling the top of a portobello mushroom to make a portobello mushroom burger.
    Lori Rice
  4. Grill the onion rounds, mushroom caps, and buns:

    Scrape the grill grates clean. Using a folded up paper towel dipped in olive oil, wipe down the grill grates to oil them.

    Brush the onion rounds with some olive oil and place them on the grill.

    Place the mushroom caps on the grill, top side down first. Sprinkle with a little salt. Grill the mushroom caps and the onion rounds for 4-5 minutes per side.

    Grill the burger buns, cut side down, for about 1/2 to 1 minute, until lightly toasted.

    Grilling red onions for a portobello mushroom burger recipe.
    Lori Rice
    Mushrooms on the grill to make a portobello mushroom burger recipe.
    Lori Rice
    Mushrooms on the grill to make a portobello mushroom burger recipe.
    Lori Rice
  5. Assemble:

    To assemble, spread some mayonnaise on each bun. Put a portobello mushroom cap on the bottom, then layer on the spinach, sun-dried tomatoes, and finally some onion. Serve at once.

    Mushroom burgers on a platter with toppings and the top bun spread with mayonaisse.
    Lori Rice