Portobello mushroom fajitas with crisp peppers and onion are loaded with all your favourite toppings for your next Taco Tuesday! The homemade fajita seasoning delivers big flavour, and these are guaranteed to please a crowd.

Mexican food is often enjoyed on Tuesdays in homes all over the globe, but this one is worth making ANY day of the week.
Inspired by my jackfruit fajitas, I wanted an umami mushroom version for the blog. And yes, these mushroom fajitas are delicious and a must-try!
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Why you’ll love these!
- Wholesome: You bet these mushroom fajitas are incredibly wholesome! They’re made using mostly vegetables, and a homemade blend of fajita seasoning. Plus, there’s no oil needed for this dish, making it virtually fat-free and VERY low in calories! 🥳
- Delicious: I wouldn’t share anything with you that wasn’t delicious, but mushroom dishes hold a very special place in my heart and these mushroom fajitas are next-level outstanding!
- Easy: SO easy to whip these up. Once you’ve sliced up your veggies, there’s not a whole lot to it. Plus this dish is ready in 30 minutes or less, making it perfect for busy weeknights, like your next Taco Tuesday. 😉
- Versatile: You can enjoy these mushroom fajitas with new toppings every time, and/or adjust the spice level to your taste.
Ingredients + Substitutions
Here’s what you’ll need to make these delicious mushroom fajitas.
- Portobello mushrooms: Portobello’s make nice, large slices, so stick to portobellos if possible. But if you don’t have any on hand, you may use any other mushroom you’d like.
- Bell peppers: I like to use a variety of colours for visual appeal, but if you only have one colour on hand, that’s fine too.
- Red onion: I like red for fajitas, but you may use yellow or white onion if you don’t have red on hand.
- Lime: Freshly squeezed is best for optimal flavour.
- Spices: I’m making my own fajita blend with six spices that I always have in my pantry. If you have a pre-mixed fajita blend you like, you may use that instead.
Instructions
(This is a summary with step by step photos, full recipe measurements and instructions are in the recipe card below.)
Add the sliced onion and peppers to a large skillet or wok with two tablespoons of water. (photo 1)
Sauté until slightly softened, without overcooking. You want the veggies tender-crisp. (photo 2)
Now add the sliced portobello mushrooms and fajita seasoning to the pan. (photo 3)
Sauté until slightly reduced, stirring often. Then turn off the heat and add the lime juice. Mix well. (photo 4)
Serve your mushroom fajitas in corn tortillas with all your favourite toppings.
What to serve with mushroom fajitas
I prefer corn tortillas, but flour tortillas are fine as well if you don’t need a gluten-free wrap option.
To keep this already low-calorie dish even lower, you can make it a bowl, and skip the wrap altogether.
Then top your mushroom fajitas with:
- Refried beans, black beans or pinto beans.
- Sliced jalapeno, pickled peppers, or hot sauce.
- Avocado slices, guacamole, salsa, or cashew cream (vegan sour cream).
- Fresh cilantro and/or lime wedges.
Equipment
I use a large well-seasoned cast-iron skillet as it retains its heat very well and sautés the vegetables quickly.
Any large pan or wok will work well for these mushroom fajitas, just make sure not to overcook your veggies.
Storage
Store any leftover mushroom fajita filling in an airtight container in your fridge for 3-4 days. Reheat the filling on the stovetop and assemble your fajita just before enjoying it.
Do not assemble fajitas in advance or the tortilla will get soggy.
I don’t recommend freezing the filling as that will alter the texture and make the veggies very soft after thawing and reheating.
Expert Tips
- Do not overcook the vegetables. They taste best when tender-crisp and not too soft.
- Prepare additional toppings in advance so once your mushroom fajita filling is ready, you can enjoy them straight away.
More recipes you’ll love
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Buon appetito
Rosa
📖 Recipe
Ingredients
- 16 ounces (454 grams) portobello mushrooms approx. 4 mushrooms
- 3 bell peppers any colour/s
- 1 red onion
- 2 tablespoons lime juice approx. 1 lime
For the fajita seasoning
- 1 tablespoon chili powder
- 2 teaspoons smoked paprika
- 1 teaspoon cumin
- 1 teaspoon garlic powder
- 1 teaspoon sea salt or to taste
- ¼ teaspoon cayenne pepper optional
For serving
- corn tortillas
- guacamole
- cashew cream
- refried beans
- jalapeno
- fresh cilantro
Instructions
- Slice the portobello mushrooms and set them aside. Then slice the peppers and onion and place them in a large cast-iron skillet or wok with 2-3 tablespoons of water. Sauté until slightly softened, without overcooking, approx. 2-4 minutes. You want the veggies tender-crisp.
- Then add the mushrooms and fajita seasoning and continue to sauté until the mushrooms are slightly reduced. Stir often. This will take approx 2-3 minutes.
- Turn off the heat and add the lime juice, then mix to combine. Taste and adjust the seasoning or lime juice if needed.
- Serve with corn tortillas and all your favourite toppings.
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