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Portobello Mushroom Fajitas

Updated August 3, 2025 / By Holly Erickson & Natalie Mortimer

A healthy, fast, vegetarian dinner is as easy and delicious as can be—meet our veggie-loaded portobello mushroom fajitas!

vegan Portobello Mushroom Fajitas on a sheet pan with tortillas

Vegan Fajitas? Vegan Fajitas!

Portobello mushrooms make a fantastic “meaty” vegetarian substitute for the traditional chicken or beef in these simple, flavorful fajitas. A dip in a lime-y marinade gives the mushrooms an extra kick of flavor, and bright bell peppers and onions add layers of texture to the finished mushroom fajitas. Top the finished fajitas with generous dollops of homemade guacamole, and indulge guiltlessly. Meatless Monday has never tasted better!

ingredients laid out for vegan fajitas, portobello mushrooms, bell peppers, onions, cilantro and tortillas
fajita sauce for vegan mushroom fajitas
vegan Portobello Mushroom Fajitas on a sheet pan
vegan Portobello Mushroom Fajitas with bell peppers on a sheet pan

Hit That Produce Aisle!

This healthy fajita recipe is really simple, and almost every ingredient comes from the produce aisle of the store—don’t you love that? It always makes us feel super virtuous to have a rainbow of produce in our grocery cart (virtual, or otherwise). And it should! Portobello mushrooms are seriously healthy—they’re a good source of copper, potassium, magnesium, zinc and even some B vitamins. If they were grown in sunlight or exposed to ultraviolet light—and many portobello mushrooms are—they can also be a good source of vitamin D.

In addition to some flour tortillas and taco seasoning, all you’ll need to make these mushroom fajitas is:

  • Portobello mushrooms (P.S. did you know that “portabella” and “portobello” are two different names for the same mushroom? We’re calling them portobellos, but the terms are interchangeable.)
  • Limes
  • Red onions
  • Bell peppers (We usually grab one of each color, to make things interesting.)
  • Cilantro

And for the guacamole (which is a must!) you’ll need:

  • Jalapeño
  • Avocados
  • Garlic
vegan Portobello Mushroom Fajitas on a sheet pan

How To Make Vegetarian Fajitas

So, much like our regular old chicken fajitas recipe, our mushroom version is also essentially a sheet pan recipe. In other words, this magical dinner recipe is vegetarian AND a one-pan meal! YAY. Here’s how to make these delicious mushroom fajitas:

  1. Slice the portobello mushrooms and toss them in taco seasoning, olive oil and lime juice.
  2. Grab your sheet pan, and load it up with the all of the vegan fajita filling goodies—sliced bell peppers, onions and the marinated portobello slices. Roast for about 20 minutes.
  3. Warm the tortillas while your mushrooms and veggies roast. You can do this in the oven, but be mindful—at 450°F, they’ll warm quickly! We usually prefer to warm them in a skillet on the stovetop.
  4. While the veggies roast, you might also want to whip up that guacamole.
  5. Serve! Fill those warm flour tortillas with the roasted mushrooms, peppers and onions, and top generously with creamy, homemade guacamole.
vegan Portobello Mushroom Fajitas on a sheet pan with tortillas
vegan Portobello Mushroom Fajitas on a sheet pan in tortillas on a plate

Tools You’ll Need:

More Easy Vegetarian Recipes You’ll Love:

Whether you’re looking for a quick meatless Monday recipe, or you’re devoted to a plant-based diet, these five vegan recipes are sure to be new favorites:

vegan Portobello Mushroom Fajitas on a sheet pan in tortillas on a plate

Healthy & Delicious—Our Favorite Combo.

Satisfying and delicious, these vegan fajitas are a sure-fire hit. If you try them, we want to hear how you liked them! Snap a photo of your portobello fajitas and tag us on Instagram using @themodernproper and #themodernproper. Happy eating!

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Portobello Mushroom Fajitas Recipe

  • Serves:  4
  • Prep Time:  10 min
  • Cook Time:  20 min
  • Calories:  160
Print Recipe

Description

A healthy, fast, vegetarian dinner is as easy and delicious as can be—meet our veggie-loaded portobello mushroom fajitas!

Ingredients

  • ¼ cup Taco Seasoning, homemade or store bought
  • 2 tablespoons extra-virgin olive oil
  • ¼ cup fresh lime juice, (from 1 to 2 medium limes)
  • 1 ½ pounds portobello mushrooms, cut into thick ½-inch slices
  • 1 small red onion, halved and cut into ½-inch-thick slices
  • 1 red bell pepper, cut into ½-inch-thick strips
  • 1 orange bell pepper, cut into ½-inch-thick strips
  • 1 yellow bell pepper, cut into ½-inch-thick strips

For serving (optional)

  • 12 (6-inch) tortillas, warmed
  • Salsa or hot sauce
  • Guacamole
  • Fresh cilantro leaves
  • Lime wedges

Method

  1. Preheat the oven to 450°F with a rack in the center position.

  2. In a large bowl, combine the taco seasoning, olive oil, and lime juice.

  3. Add the portobello mushrooms to the bowl and toss until evenly coated.

  4. Spread the mushrooms, onion, and bell peppers on a rimmed sheet pan. Bake for 20 minutes. If desired, turn the oven to broil and cook for 3 more minutes, or until the peppers are lightly charred.

  5. Serve with warm tortillas, salsa, guacamole, fresh cilantro and limes wedges, if using.
     

Nutrition Info

  • Per Serving
  • Amount
  • Calories 160
  • Protein 8 g
  • Carbohydrates 23 g
  • Total Fat 8 g
  • Dietary Fiber 5 g
  • Cholesterol 0 mg
  • Sodium 241 mg
  • Total Sugars 7 g

Portobello Mushroom Fajitas

Questions & Reviews

Rated 5 stars by 14 readers

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  • Sally

    No directions for the peppers!

    You add them to the pan with the mushrooms in step 3. Hope you enjoy Sally!

  • Tamara

    Only marinade the mushrooms? Don’t add the peppers?

    We usually just do the mushrooms, yes.

  • Jess

    If I didn’t read the blog and only read the recipe I would have completely missed the “marinade for one hours”. I don’t see it in the actual recipe, could be missing it. Still good with less marinade time ?

    Thanks for bringing this to our attention Jess! We will update the instructions. It will still be good if you don't marinade for an hour.

  • Gordon

    These are not GF as advertised since they call for flour tortillas

    Hi Gordon, you can just swap for corn tortillas to make it gluten free. Hope you enjoy!

  • Su

    What can I serve this with in order to get more protein in the meal? Preferably, a vegetarian source of protein.

    We really love soy curls! They'd be delicious in this. Or you could add some veggie sausage!

  • Shanita

    5-star rating

    Delicious!

    Thanks Shanita, so happy you love it!

  • Linz

    5-star rating

    OMG this recipe was SO good. I can't get over how amazing the mushrooms are (and I don't love mushrooms) I marinated them for about 1 hour before roasting and I also added some olive oil and balsamic vinegar to the marinate. It was delicious!

    Thanks Linz, so glad you loved it!

  • Sophia

    5-star rating

    Absolutely amazing, the flavours were perfect!

    Thanks Sophia, we are so glad you loved it!

  • Karla

    5-star rating

    My husband and I are meat lovers. However, we are trying to incorporate more plant based options in our diet. We both loved this. Thank you!

    Thanks Karla, we are so happy you loved it! Our Kung Pao mushrooms are a super delicious plant based option, you should check it out!

  • Douglas

    5-star rating

    This is remarkably good! I marinaded the mushrooms for an hour, and I drizzled a little olive oil over the peppers and onion before baking. It's a lot while raw, but it reduces once cooked. I cooked what didn't fit on the cookie sheet in a cast iron stove-top, which may have been even better. This is a winner. I'll do it again!

    Thanks Douglas, we are so happy you enjoyed it!

  • Mary

    5-star rating

    Excellent. Had all the ingredients and some portabellos I didn't have a real plan for. Prefect dinner
    Quick and tasty. Thanks?

    Thanks Mary Ann, we are so glad you loved it!

  • Briana

    5-star rating

    I tried this recipe! It was absolutely delicious! *chef’s kiss* My favorite! Thank you so much for sharing this meal, especially because it’s meatless!

    Thanks Briana, we are so glad you loved it!

  • Beatrix

    5-star rating

    This was amazing!!! I made it on the grill to get a nice smokiness which was phenomenal, also made your taco seasoning in the link. I didn't do the oil as I was scared it might burn on the fire, I just sprinkled quite a bit over it before and during cooking. I loved this so much!!

    Thanks Beatrix, we are so glad you love these!

  • Tara

    5-star rating

    This is now one of my family’s go to meals. So tasty and easy and is now part of our dinner rotation!

    WOW! That is so great to hear, thanks Tara! We are so happy your family loves it!

  • Eri

    5-star rating

    This was absolutely delicious! Thank you for the recipe! I added cilantro rice. Made for some very fat tacos!

    Thanks Erica! SO happy you loved these!

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