Sheet Pan Portobello Fajitas

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.

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! 

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Sheet Pan Portobello Fajitas

4.80 from 30 votes Sheet Pan Portobello Fajitas are an easy and flavorful vegetarian dinner idea that all cooks on one pan for easy cleanup! Author: Beth – Budget Bytes Servings 4 (two fajitas each) Prep 15 minutes Cook 40 minutes Total 55 minutes Save RecipeSaved! Print Recipe



  • 1 Tbsp chili powder* ($0.30)
  • 1/2 tsp chipotle powder ($0.05)
  • 1/2 tsp onion powder ($0.05)
  • 1 tsp cumin ($0.10)
  • 1/2 tsp garlic powder ($0.05)
  • 1 tsp sugar** ($0.05)
  • 1/2 tsp salt ($0.03)


  • 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)


  • 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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Enamelware Sheet Pan


*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.


Serving: 1ServingCalories: 423kcalCarbohydrates: 49gProtein: 9gFat: 23gSodium: 782mgFiber: 9g Read our full nutrition disclaimer here. Have you tried this recipe?Mention @budgetbytes or tag #budgetbytes on Instagram!

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

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. 

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

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.

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

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.

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. 

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

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

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

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