Portobello Mushroom Fajitas
Published Apr 19, 2026
These quick and easy Portobello Mushroom Fajitas are an absolutely delicious vegetarian dinner recipe! Serve with flour tortillas and avocado slices for a meatless meal that is sure to impress.
Portobello Mushroom Fajitas
These meatless fajitas are a flavorful dinner so memorable it will impress even the pickiest meat eater!
Thick strips of mushroom are roasted to caramelized perfection along with sliced bell pepper and onion.
Juicy portobello mushrooms are the star of these fajitas. They are one of my favorite “meaty” veggies to use in vegetarian dishes.
The combination of high heat and homemade fajita spice mix results in the most delicious tender and juicy flavorful mushrooms. I could eat these straight off the pan they are so good!
Ingredients Needed
- Portobello mushroom caps: these “meaty” mushrooms give this recipe a hearty taste.
- Onion: we prefer yellow or white onions for this recipe.
- Bell pepper: any color you want. We used half red and half orange.
- Spices: This homemade fajita spice mix is made of salt, cumin, chili powder, garlic powder, onion powder, and paprika.
- Olive oil: to coat the veggies in for roasting.
- Fresh lime juice
- For serving: small flour tortillas and avocado slices.
How to make portobello mushroom fajitas
Step 1: Preheat the oven to 400 degrees. Slice the mushrooms, onion, and bell pepper into thick slices and place them on a large sheet pan.
Step 2: Make your homemade fajita spice mix. Stir together the salt, cumin, chili powder, garlic powder, onion powder, and paprika.
Step 3: Sprinkle the fajita spice mix over the vegges and drizzle the olive oil over the top. Use your hands to toss the veggies until they are coated evenly in the oil and spices.
Step 4: Roast the fajita veggies in the oven for 20 minutes, then stir and toss them. Roast the veggies for an additional 15-20 minutes, until caramelized.
Step 5: Squeeze the fresh lime juice over the top of the veggies and toss to combine. Serve with flour tortillas, avocado slices, and toppings of choice.
The high heat used in roasting these veggies is key for getting those charred and crispy caramelized edges that give the dish so much flavor!
Toppings
Be sure not to skip the fresh avocado slices with these fajitas! The creamy cool avocado is the perfect contrast to the smoky vegetables.
If you want more topping ideas, you could try homemade guacamole, sour cream, salsa, or jalapeños for a little heat.
Storing
Leftover fajita filling can be stored in airtight container in the refrigerator for up to 3 days. Reheat leftovers on a sheet pan in the oven until hot.
Try these portobello mushroom fajitas for your next Meatless Monday!
More Easy Vegetarian Recipes
Portobello Mushroom Fajitas
Ingredients
- 4 large portobello mushroom caps, cut into thick slices
- 1 onion, sliced
- 1 bell pepper, sliced
- 1 teaspoon salt
- 1 teaspoon cumin
- 1 teaspoon chili powder
- 1 teaspoon garlic powder
- ½ teaspoon onion powder
- ¼ teaspoon paprika
- ¼ cup olive oil
- 1/2 lime, juiced
For serving
- small flour tortillas
- avocado slices
- lime wedges
Instructions
- Preheat the oven to 400 degrees.
- Slice the mushrooms, onion, and bell pepper and place them on a large sheet pan.
- Stir together the salt, cumin, chili powder, garlic powder, onion powder, and paprika in a small bowl to make the spice mix.
- Sprinkle the fajita spice mix over the veggies and drizzle the olive oil over the top. Use your hands to toss the veggies until they are coated evenly in the oil and spices
- Roast the portobello mushroom fajita veggies in the oven for 20 minutes, then stir and toss.
- Roast the veggies for an additional 15-20 minutes, until caramelized.
- Squeeze 1/2 of a lime over the top of the veggies before serving. Toss to combine.
- Serve the fajita filling on small flour tortillas with avocado slices or toppings of choice.
