Sheet Pan Portobello Fajitas

$10.81 recipe / $2.70 serving
by Beth - Budget Bytes
4.83 from 34 votes
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I got that craving for fajitas the other day and just had to have ’em. I decided to switch things up a bit from my usual sheet pan fajitas and use portobello caps in place of the chicken. I also added a little smoky chipotle powder to the spice mix to keep things interesting. These Sheet Pan Portobello Fajitas are a new and welcome twist on the classic. A little squeeze of lime on top and a slice or two of creamy avocado, and you have a really tasty veggie-filled dinner.

Three Portobello Fajitas on a plate.

Portobello Mushrooms on a Budget

Portobello mushrooms aren’t the cheapest item in the produce aisle, so it’s important to use some of our budget byting principles here. First, make sure you compare prices both between available grocery stores and even within the store. If your grocery store sells them both packaged together and loose, be careful to compare the per-pound price because it might be cheaper to buy them loose! 

Second, we’re going to combine the portobello mushrooms with other ingredients that are much less expensive, like onions, bell peppers, and tortillas to balance out the total price and keep the price per serving on the low side. 

Make it Spicy or Mild

The recipe, as written below, is a little smoky and spicy thanks to the chipotle powder in the fajita spice mix. If you prefer a mild fajita, skip the chipotle powder and make sure to use a chili powder blend that is mild. If you want your fajitas to be smoky but not spicy, replace the chipotle powder with smoked paprika. 

Meal Prep It!

The filling for the fajitas works great as a meal prep. Just pack up the roasted mushroom, pepper, and onion mix in a lunch container with a slice of lime and a couple of tortillas. When it’s time for lunch, remove the tortillas and lime, reheat, then fill the tortillas, squeeze your lime, and enjoy!

For the avocado, I suggest slicing a few slices off the whole avocado each day. Only the exposed surface will darken, and it only darkens slightly (it doesn’t turn completely black like mashed avocado). The darkening of the avocado does not mean it is spoiled, it just means that it has been exposed to oxygen (like a brown apple), and is still perfectly safe to eat.

What to Serve with Portobello Fajitas

Sweet Corn Salsa or Summer Sweet Corn Salad would be a wonderfully light and fresh contrast to these portobello fajitas. And if you want to dress them up a little bit more you could whip up a quick batch of Guacamole or Pico de Gallo

Roasted portobello and vegetables on a sheet pan.
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Sheet Pan Portobello Fajitas

4.83 from 34 votes
Sheet Pan Portobello Fajitas are an easy and flavorful vegetarian dinner idea that all cooks on one pan for easy cleanup!
Three portobello fajitas on a plate.
Servings 4 (two fajitas each)
Prep 15 minutes
Cook 40 minutes
Total 55 minutes

Ingredients

FAJITA SPICE MIX

FAJITAS

  • 2 portobello mushroom caps ($3.99)
  • 2 bell peppers (any color) ($2.29)
  • 2 yellow onions ($0.64)
  • 3 Tbsp olive oil ($0.38)
  • 8 small flour tortillas (6-inch) ($1.00)
  • 1 avocado ($1.09)
  • handful cilantro (optional) ($0.25)
  • 1 fresh lime ($0.59)

Instructions 

  • Preheat the oven to 400ºF. In a small bowl, stir together all the ingredients for the fajita spice mix
  • Slice the portobellos, bell peppers, and onions into 1/4 inch wide strips. Place the sliced vegetables on a large sheet pan. Drizzle the olive oil over the vegetables then sprinkle the fajita spice mix over top. Use your hands to toss the vegetables until everything is well coated in oil and spices.
  • Roast the vegetables in the fully preheated oven for 40 minutes, or until the vegetables are slightly wilted and the edges have a nice brown color. Stir the vegetables half way through the roasting time to make sure everything gets even exposure to the hot air.
  • After removing the vegetables from the oven, squeeze fresh lime juice over top. Sprinkle chopped cilantro over the vegetables. To serve the fajitas, scoop a small amount of the roasted vegetables into each tortilla and add a slice of avocado.

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Notes

*The chili powder I use is a mild blend made by McCormick. It is not spicy at all and contains barely any salt. If using a different brand, make sure to adjust the salt and/or chipotle accordingly.
**The small amount of sugar in this recipe helps caramelize the vegetables and give everything that grilled or charred flavor that is characteristic of fajitas.

Nutrition

Serving: 1ServingCalories: 423kcalCarbohydrates: 49gProtein: 9gFat: 23gSodium: 782mgFiber: 9g
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side view of three portobello fajitas on a plate.

How to Make Sheet Pan Portobello Fajitas – Step by Step Photos

Fajita spices in a wooden bowl.

Begin by preheating the oven to 400ºF. In a small bowl, stir together 1 Tbsp chili powder, 1/2 tsp chipotle powder, 1/2 tsp onion powder, 1/2 tsp garlic powder, 1 tsp cumin, 1 tsp sugar, and 1/2 tsp salt. 

Whole vegetables on a cutting board.

I used 8 oz. portobello caps (2-3 depending on their size), two bell peppers (any color), and two yellow onions for my fajitas.

Sliced vegetables on a baking sheet.

Slice the vegetables into strips about ¼-inch wide. I also cut the portobello strips in half, so the pieces aren’t quite so large. Place the sliced vegetables on a large sheet pan.

Spices being sprinkled over the sliced vegetables.

Drizzle 3 Tbsp olive oil over the vegetables, then sprinkle the prepared fajita seasoning over top.

Seasoned vegetables ready to roast.

Use your hands to toss the vegetables in the oil and spices until everything is evenly coated, then make sure the vegetables are spread out over the baking sheet in an even layer.

Roasted vegetables on the sheet pan.

Roast the vegetables in the preheated oven for 40 minutes, or until they are slightly wilted and have browned on the edges. Stir the vegetables halfway through the roasting time to make sure everything gets even exposure to the hot air. 

Finished fajita vegetables on the baking sheet with lime and cilantro.

After roasting, squeeze lime juice over the vegetables and top with chopped cilantro.

Three portobello fajitas on a plate.

To serve, scoop a small amount of the fajita vegetables into each small tortilla and add a slice of fresh avocado.

Overhead view of the fajita vegetables on a sheet pan.

Seriously, these Chipotle Portobello Oven Fajitas are probably one of my favorite vegan recipes!

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  1. Just had these for dinner tonight and these will be on repeat at our home. I went a little over time with 40 mins in our oven. They got slightly charred but yummy nevertheless. Next time I will do only 30 mins and they will be perfect. We had these with all the fixings (guacamole, tomatillo salsa, pickled hot green chiles, homemade yogurt dip and topped with some chili lime chili hula) Hubbby and Kiddo added their fav. Meats but I gobbled my taco up as is. This receipt is so delicious and hands free that it is a perfect busy weeknight dinner. Next time I will bake a big batch for meal prep. Thanks Beth!! 

  2. Rather than spreading all the sliced vegetables on the baking sheet, why not toss in a bowl or ziplock bag with the oil and spices, and then put on the baking sheet. Seems more logical to me!

  3. Just a question in general not necessarily related to this recipe. When you post that a recipe is updated, what gets changed? Just the pricing or the process and ingredients, too?

    1. Hi Julie, We re-test the recipe and make any changes we feel are necessary to make it even better. We also photograph it again and update ingredients and pricing. XOXO -Monti

  4. This recipe was phenomenal. My husband is a huge meat eater and even he loved this and said he prefers these over the steak fajitas from our local Mexican restaurant. I made a few minor changes, mostly because we have a 1 year old daughter who eats what we eat and I didn’t want it to be too spicy for her. So I reduced the chili powder to 2 tsp and used smoked paprika instead of chipotle powder. My only regret is that my avocados were not ripe LOL

  5. If you follow it exactly as written out in the recipe, they are wonderful! I did not have an issue with sogginess or anything really. This is such an easy, delicious meal! It also feels really wholesome.

  6. I’m not the biggest fan of portobello mushrooms and also wanted to get a little more protein into this recipe. So I subbed a mock meat (Quorn beef strips) for the mushrooms and it was great! Simple but flavorful approach to fajitas that really hit the spot. (FYI I did exclude onion due to an allergy.)

  7. I never review much, but I have to comment how good these are. My family thought we would miss the meat, but we didn’t. Using the little bit of sugar with the spices to mimic the pan-fried caramelization is brilliant! It makes preparing fajitas so much easier. Cutting the vegetables 1/4 inch as noted and using large lined sheet pans seems to give us the best results as it allows plenty of room to let liquid evaporate and a ton of flavorful caramelization to occur. I even double the recipe across two sheet pans to make sure we have leftovers. Everyone just snarfs this stuff up! This is a regular in our household now.

  8. Mine ended up very soggy and not browned like I would have wanted. Makes for very drippy tacos. Still, the flavor is good. I served it with corn, pan fried potatoes, and refried beans. Definitely good for a meal, not so much for meal prep because they are so soggy.

  9. Just want to say that we make this ALL the time because it’s so easy and so good! It’s perfect as-written, but oftentimes we end up making it with just peppers (just depends on what we have on-hand), but love how adaptable it is. We tend to always try to have peppers in the fridge since we know that about once a week we’ll feel like making this recipe!

  10. !So good!! I’ve been looking for more plant based recipes and this is awesome ! I will be eating this all of the time!

  11. I love this recipe! In fact, I prefer it over the chicken fajitas. I also add sour cream to the tortilla and it is delicious!

  12. Great flavors, nice combination of textures. The roasted peppers and mushroom caps blend well. This is going to be my new favorite

  13. We made this recipe for dinner tonight – SO GOOD! We had four ‘bello caps to use up and cooked them all. Some shrimp might be tasty with this as well. Thank you!