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These roasted Portobello Mushroom Fajitas are a delicious meatless meal that even steadfast meat eaters will love. Marinated portobello mushrooms are roasted with bell peppers and onions and piled on toasted tortillas with toppings to create these easy vegetarian fajitas.
I made these Portobello Mushroom Fajitas for my meat loving group here and I was astounded at how good they were. So good, in fact, that they are now a regular on our menu. And, friends, they are fast! They’re ready in under 40 minutes, making them a great busy weekday meal.
I’ve been including at least one meatless meal on my menu plan every week and this one is spot on perfect to work for my family. They are Mexican food fans through and through so anything tucked inside a tortilla is a natural fit. Whether you load them with toppings or just keep it simple, they are amazing.
- Portobello mushrooms – These large mushrooms have an exceptionally meaty texture and work really well as a meat replacement. They are excellent at soaking up flavor from marinades and hold up better than small mushrooms when roasted. See the FAQ section below for more details.
- Red onion
- Bell peppers – I like to use red, yellow, and orange bell peppers which have a sweeter, milder flavor than green.
- Olive oil
- Kosher salt and freshly ground black pepper
- Lime juice – From one fresh lime. You might want to have another lime or two on hand for serving or for dressing the avocado (if using).
- Granulated garlic, coriander, smoked paprika, cumin – This combination of spices is combined with olive oil and lime juice to create the smoky, flavorful mushroom marinade.
- Black beans – I love to serve these with warmed black beans. An optional but yummy addition.
- Flour tortillas – I use street taco sized (5-inch) flour tortillas. They work great for these mushroom fajitas and they also help with managing portion size.
- Crumbled cotija cheese – This hard, salty cheese is the perfect complement to smoky portobello mushrooms. Try it!
- Avocado – Slice an avocado and toss it with a little lime juice.
- Sour cream – Light or regular
- Hot sauce – Gotta have it in this house!
Portobello Mushroom FAQ
Choose portobellos with caps that measure 4- to 6-inches across. They should be dry and firm. Avoid any with soft or slimy caps.
They are best stored in a paper bag in the refrigerator. If they are wrapped in plastic when you bring them home from the store, remove it. If you don’t have a paper bag, you can wrap them in paper towels instead or place them on a tray, covered with paper towels. Keep them refrigerated and use them within 1 week.
Place them, cap side up, under running water and rinse them well. Pop off the stems, if the recipe calls for it, and run water through the gills on the underside. Pat the mushrooms dry with a paper towel.
How to Make Portobello Mushroom Fajitas
Preheat oven to 450 degrees F. Coat a large rimmed baking sheet with nonstick cooking spray (I use avocado oil spray).
- Core and slice the peppers and onion into ¼-inch thick slices and place in a large mixing bowl.
- Drizzle the veggies with olive oil, a little kosher salt, and freshly ground black pepper and toss well to coat the veggies.
- Pour them on to the baking sheet, spreading them out across the pan. Transfer to the oven for 10 minutes.
- While the peppers and onions roast, remove the caps from the mushrooms and slice them ¼-inch thick and place them in the empty bowl (it will still be oily from peppers and onions). In a separate small bowl, combine the marinade ingredients. Pour the marinade over the mushrooms and toss lightly until evenly coated.
- After the initial 10 minute cooking time, remove the baking sheet from the oven and push the peppers and onions to one half of the baking sheet.
- Pour the mushrooms out over the other half and spread them out. Return the baking sheet to the oven and continue to roast for an additional 10 to 12 minutes, or until the veggies are tender.
For the Tortillas
To prepare the flour tortillas, place a dry skillet over medium-high heat. Add as many tortillas as will fit comfortably and toast for a minute or two, per side, or until nicely toasted Transfer them to a tortilla warmer until you are ready to serve.
Add More Protein
For additional protein and even more great flavor, add a can of black beans. Rinse and drain the beans and warm them gently in a saucepan.
Fajitas for a Crowd
To make these for a larger group, double the ingredients and use two baking sheets – one for the peppers and onions and one for the portobello mushrooms. Mushroom fajitas are a healthy game day party choice or a fast and easy dinner anytime.
More Wholesome Mexican Meals
Portobello Mushroom Fajitas
- 1 pound portobello mushrooms, stems removed (about 4 mushrooms)
- 1 medium red onion
- 3 small to medium bell peppers assorted colors (red, orange, yellow – no green)
- 2 tablespoons olive oil
- ¼ teaspoon kosher salt
- ¼ teaspoon freshly ground black pepper
- 1 lime juiced
- 2 tablespoons olive oil
- 2 teaspoons smoked paprika
- 1 teaspoon cumin
- ½ teaspoon coriander
- ½ teaspoon granulated garlic or garlic powder
- ½ teaspoon kosher salt
- ½ teaspoon freshly ground black pepper
For the Rest
- 15 ounce can black beans rinsed and drained
- 8 to 10 street taco sized (5-inch) flour tortillas toasted in a dry skillet
- sliced avocado tossed with lime juice
- cilantro leaves
- cotija cheese crumbled
- sour cream
- hot sauce
- Preheat oven to 450 degrees F. Coat a large rimmed baking sheet with nonstick cooking spray (I use avocado oil spray).
- Core and slice the peppers into ¼-inch thick slices and place in a large mixing bowl. Slice the onion in half and then into ¼-inch thick slices and add to the bowl with the peppers. Drizzle the veggies with 2 tablespoons olive oil, ¼ teaspoon kosher salt, and ¼ teaspoon pepper. Toss well to coat the veggies and pour them on to the baking sheet, spreading them out across the pan. Transfer to the oven for 10 minutes.
- Meanwhile, remove the caps from the mushrooms and slice them ¼-inch thick and place them in the empty bowl (it will still be oily from peppers and onions).
- In a separate small bowl, combine the marinade ingredients. Pour the marinade over the mushrooms and toss lightly until evenly coated.
- After the initial 10 minute cooking time, remove the baking sheet from the oven and push the peppers and onions to one half of the baking sheet. Pour the mushrooms out over the other half and spread out as much as possible (it's okay if they aren't in a single layer, they'll shrink slightly as they cook). Return the baking sheet to the oven and continue to roast for an additional 10 to 12 minutes, or until the veggies are tender.
- Meanwhile, add the black beans to a small saucepan and heat over low heat until warmed through.
- Place a skillet over MEDIUM-HIGH heat. Add as many tortillas as will fit comfortably and toast for a minute or two, per side, or until nicely toasted.
- Serve on toasted tortillas with black beans, avocado, cotija, sour cream, hot sauce, and cilantro.
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