Sheet Pan Portobello Fajitas (Vegan)

Sizzling and spicy bell pepper, onion, and portobello mushroom strips will make truly delicious vegan fajitas together with guacamole, salsa, black beans, and vegan sour cream. I guarantee you that you will not miss any beef or chicken. It is quick to make, but even quicker to disappear. 

Hands up who loves Mexican or Tex-Mex food? We sure do. They burst in flavor, rich and colorful. Just look at our vegan bean chili recipe. So much color! Whether it is a burrito, a burrito bowl, some tacos, or these mushroom fajitas… they are perfect for a quick lunch or dinner. If you need even more quick and easy recipes, check out our quick vegan meals collection. 

What to expect from this recipe

Fajita is Mexican or Tex-Mex comfort food. They serve it usually as a do-it-yourself meal. You get a sizzling hot cast iron with fajita veggies and beef or chicken strips and several small bowls of different toppings like guacamole, some kind of tomato-based salad or sauce, sour cream, refried beans, shredded cheese as well as some soft tortillas. You can then mix and match and fill the tortillas according to your taste. 

This recipe is exactly the same minus beef and chicken of course. We show you the easiest way to make fajitas filling in the oven as well as how to make the various add-ins and toppings to make it a full-course meal. There are so many delicious ingredients here that you will not even realize that at the end you are eating a meatless meal.

Ingredients

If you want to make portobello fajitas, you really don’t need to change or substitute a lot of things since apart from sour cream all other ingredients are usually vegan as they are. So what do you need?

🛒 You can find detailed measurements for all ingredients in the printable version of the recipe card at the bottom of this post.

Soft tortilla

Let’s start with a tortilla. You need soft tortillas as fajitas are generally eaten rolled up or folded in half. Most of the store-bought wheat or corn tortilla brands are vegan.

However, if you need vegan and gluten-free as well, we recommend trying these coconut flour tortillas or these multi-grain tortillas.

We also have a homemade flourless grain-free tortilla recipe (made of red lentils and buckwheat) that we use a lot in different Mexican or Tex-Mex dishes. 

Fajita veggies

You need bell peppers, onions and if you like it hot, then some chili peppers. We have a detailed guide on how to make fajita veggies the EASIEST WAY. It includes how to cut the vegetables, how to roast them, and how to make your homemade fajitas seasoning. If you only need a small batch (like dinner for two), you can find our step-by-step guide to pan-fry fajita veggies in our copycat chipotle veggie bowl recipe. 

Mushroom strips

There are several alternatives to choose from if you prefer whole foods substitution. Some of them will be closer to beef in terms of texture and taste, while some of them will be far from it. In any case, with strong spices and seasoning, you will like the meaty spongy texture of portobello mushrooms for sure.

Alternatively, you can try it with oyster mushrooms. They are the best vegan shredded chicken ever.

Toppings and add-ins

Our favorite toppings for vegan portobello mushroom fajitas are

• Guacamole – We usually make a copycat Chipotle guacamole.
• Chunky salsa sauce – You can choose mild or hot depending on your taste. This brand should be vegan and gluten-free.
• Black beans – We actually like using this canned black bean soup since the black beans there are even more flavorful. , 
• Sour cream – We like to use Dr. Oetker’s vegan sour cream, but if you want a homemade recipe that is nut-free as well, try our vegan sour cream.
• Lime
• Cilantro

Instructions

Our favorite method to make vegan fajitas is roasting mushroom, bell pepper, and onion slices in the oven.

Why? Because…

• it is easy and has no mess, 
• you can make a much larger batch than in a skillet, and
• you can do other things in the kitchen while the oven is busy roasting. 

For detailed steps, top tips, video, and more guidance visit our fajita veggies post.

Prepare ingredients

• Peel and slice onion ¼-inch (4-5 mm) wide.
• Wash and slice bell peppers also ¼-inch (4-5 mm) wide.
• Rinse portobello mushrooms if they are really dirty. Otherwise, just gently wipe them with a damp towel. Take out the stem and slice them also ¼-inch (4-5 mm) wide.

Roasting veggies

1. Mix your spices (hot chili powder like chipotle powder, sweet smoked paprika, cumin, garlic powder, oregano).
2. Place parchment paper in a sheet pan and place the prepared mushroom, bell pepper, and onion slices on it.
3. Sprinkle them with olive oil and season them with half of the spice mix plus salt and pepper. Mix with tongs.
4. Roast them in a preheated oven of 430 Fahrenheit (220 degrees Celsius). After 10 minutes, take the sheet pan out, turn the veggies with tongs and sprinkle them with the other half of the spice mix. Roast them for 10 more minutes. 

Making guacamole

We have several copycat Chipotle vegan recipes among others their burrito, their veggie bowl, their sofritas, and well their guacamole.

Chipotle tweeted its guacamole recipe in May 2019. Here is how you can make it.

1. Take one ripe avocado and mash it with a fork.
2. Add lemon or fresh lime juice.
3. Add finely chopped red onion and finely chopped fresh cilantro.
4. Mix it well and season it with salt if needed.

Building your portobello fajitas

1. Take a soft tortilla.
2. Place a couple of mushrooms, bell pepper, and onion slices in the middle.
3. Scoop 2 Tablespoons of guacamole, salsa, black beans, and sour cream on top.
4. Fold them up and enjoy!

Top tips to make them perfectly

• Use a sheet pan with parchment paper. We recommend using a sheet pan because it has sides. If you use a baking sheet, the juices from the veggies during roasting might flow off of it. 
• Cut veggies into equal strips. This is to make sure the vegetables are ready at the same time.
• Place veggies in batches on the sheet pan. If they are grouped together, they will be easier to mix and match and serve. 
• Hot and sweet together? – In case you prepare these portobello fajitas for kids or for people who don’t like spicy food, roast hot chili peppers separate from all other veggies. If you roast hot chili peppers and bell peppers together, the juices of the hot chili peppers may make the sweet bell peppers also spicy and hot.
• Other ways to make fajita veggies. After preparing and cutting your veggies you can use other ways to get them ready like 1) Sautee them in a cast-iron skillet or grill pan or griddle or 2) Grill them in aluminum foil drip pans on your BBQ. -> In our vegan burrito bowl recipe, we show you with step by step pictures of how to pan-fry fajita veggies. 

What else can you add?

Well, there are lots of tasty things that come to my mind to add to these portobello fajitas:

• shredded lettuce, 
• shredded vegan cheese, 
• hot sauce,
• other fresh salsa, (here is a savory-sweet pineapple mango salsa recipe from Caramel and Cashews or this tomato corn salsa fresca in our burrito bowl recipe)
• queso cheese dip, (try our vegan queso dip)
• nacho cheese sauce, (try our vegan nacho cheese sauce).

FAQs

How to store them?

You can store any leftovers in an airtight container in the fridge for 2-3 days without a problem. Reheat them in a pan or in a microwave.

Can you freeze them?

Yes, you can store it in a freezer. Make a larger batch ahead and froze them for later use. Thaw them and reheat them in a pan before serving.

Allergen info

This vegan portobello fajitas recipe is meat-free, dairy-free, and egg-free.

• Vegan – All ingredients are supposed to be vegan.
• Nut-free – All ingredients are supposed to be nut-free but check for cross-contamination info on all packaging you need. Especially check the vegan sour cream you are about to use since a lot of brands uses coconut as a base. You can try our homemade sour cream recipe which is nut-free.
• WFPB-friendly (whole foods plant-based) – You can roast vegetables without oil as well. Mix the spices with a bit of water instead of oil. Spread it around the slices and roast them like that. They will be a bit drier and will be easier to blacken. So pay attention to the baking time.
• Gluten-free – Most soft and corn tortillas are vegan, but not gluten-free. We recommend trying these coconut flour tortillas or these multi-grain tortillas. Or try our homemade flourless grain-free tortilla recipe (made of red lentils and buckwheat) that we use a lot in different Mexican or Tex-Mex dishes. All other ingredients should be gluten-free but look for certified store-bought products for salsa, canned beans, and sour cream.
• Soy-free – Especially check the vegan sour cream you are about to use since a lot of brands uses soy as a base. You can try our homemade sour cream recipe which is soy-free. All other ingredients are supposed to be soy-free.

More vegan Mexican recipes

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UPDATED: This recipe was originally posted in Jan 2020. More tips, step photos, and info were added and it was republished in Sep 2022.