Author: About Nicole  | Published by: Lettuce Veg Out

Vegan Fajitas with Portobello Mushrooms

This flavor-packed vegan fajitas recipe is made with Portobello mushrooms and other tasty veggies. It’s marinated for maximum flavor and baked on a sheet pan for super easy cooking.

Serve this mushroom filling in tortillas with all your favorite toppings for a crowd-pleasing meal! This recipe can be made gluten and soy-free if needed.

veggie fajitas recipe ingredients

The ingredients for this recipe are simple but work together to create mouth-watering fajitas.

  • Portobello mushrooms: Mushrooms are the star of this recipe. Portobellos are meaty, earthy mushrooms that many vegans use as a steak replacement. You can use other types of mushrooms, but Portobellos are best for their texture and size.
  • Bell peppers: Use any colored bell peppers you like for a tasty fajita veggie mix.
  • Onion and garlic: Fajitas are typically made with lots of onion as a main vegetable and it’s a great way to add flavor. Garlic is also a must for me as I include this tasty ingredient in almost all my recipes.
  • Vegetable oil: Some oil helps the veggies cook nicely, not stick to the pan and roast to slightly blackened perfection. Use any neutral-tasting vegetable oil you like; I typically use avocado oil for this recipe.
  • Soy sauce: While this isn’t a typical fajita ingredient, the saltiness and umami flavor of soy sauce creates a rich-tasting dish. This is especially helpful when trying to make a vegan meal taste as delicious as something that would typically include meat. Use tamari for a gluten-free option or coconut aminos for a gluten and soy free option.
  • Lime juice: Fresh lime juice elevates all the flavors in these fajitas. The acidity and bright flavor heightens every other ingredient. You could use lemon juice, but lime has the best flavor for making veggie fajitas.
  • Agave syrup: Some sweetness helps balance flavors and agave syrup has the perfect flavor to pair with fajitas. You may want to use maple syrup instead.
  • Tomato paste: Concentrated tomato flavor is a great addition to fajitas. The flavors of tomato paste become more complex and caramelized as the fajita veggies roast.
  • Nutritional yeast: This tasty ingredient adds a nice depth of flavor to the recipe. Nutritional yeast is slightly nutty and cheesy in taste, adding an extra layer of umami flavor. Nutritional yeast is NOT the same as traditional yeast and these ingredients cannot be substituted for one another.
  • Taco seasoning: To keep things simple, I use homemade taco seasoning for the spice blend in this recipe. Use any taco or fajita seasoning mix that you like (homemade or store-bought).
  • Cilantro: While technically optional, chopped, fresh cilantro helps add lots of flavor to these fajitas. Since the veggies have a bold, spicy flavor, cilantro helps brighten that. A drizzle of extra lime juice could also work if you aren’t a fan of cilantro.

Vegan Fajitas with Portobello Mushrooms

  • Prep Time20 min
  • Cook Time30 min
  • Total Time50 min
  • Yield6 Fajitas


    • 6 large portobello mushrooms (375 grams)
    • 3 cups onion (about 1 large, 210 grams)
    • 4.5 cups bell pepper (about 3 medium, 475 grams)
    • 6 cloves garlic
    • 4.5 tablespoons vegetable oil (45 milliliters)
    • 4.5 tablespoons soy sauce (or tamari, 45 milliliters)
    • 3 tablespoons lime juice (30 milliliters)
    • 3 tablespoons agave syrup (30 milliliters)
    • 3 tablespoons tomato paste (30 milliliters)
    • 3 tablespoons nutritional yeast
    • 2.25 tablespoons taco seasoning

    To Serve

    • 0.75 cup cilantro, chopped (optional, 10 grams)
    • tortilla wraps
    • extra toppings


    Step 1: Slice Vegetables

    • Chop your mushrooms and other vegetables into a container with seasonings.
      6 large portobello mushrooms,3 cups onion,4.5 cups bell pepper,6 cloves garlic,4.5 tablespoons vegetable oil,4.5 tablespoons soy sauce,3 tablespoons lime juice,3 tablespoons agave syrup,3 tablespoons tomato paste,3 tablespoons nutritional yeast,2.25 tablespoons taco seasoning
    • Secure a tight-fitting lid to the container.

    Step 2: Marinate Veggies

    Refrigerate and let the vegetables marinate for at least 2 hours (overnight is best).

    Step 3: Bake and Serve

    • When the vegetables are marinated, preheat your oven to 425 °F.
    • Place the vegetables onto a baking tray in an even layer.
    • Bake 25-35 minutes, until the vegetables are cooked and starting to crisp on top.
    • For more of a blackened option, place the vegetables under a broiler on high for 1-2 minutes (keeping a very close eye on it so it doesn’t burn).
    • When out of the oven, sprinkle your vegetables with chopped cilantro.
      0.75 cup cilantro
    • Serve in tortillas with all your favorite fajita toppings.
      tortilla wraps,extra toppings


    1. Nutrition information analyses this recipe for marinated vegetables only and does not account for tortilla wraps or other toppings used to serve (like sour cream).
    2. Time to make recipe only includes active prep and cooking times; marinade time is listed for reference but not included in total.
    3. Accuracy of nutrition information cannot be guaranteed (certain ingredients may not have all nutrients listed in the database); amounts may vary (and will vary depending on brands of ingredients used); all nutrition fact values rounded to the nearest whole number.


    Serving: 1 Fajita (¼ of recipe) | Calories: 229 kcal | Carbohydrates: 29 g | Protein: 7 g | Fat: 11 g | Saturated Fat: 1 g | Polyunsaturated Fat: 2 g | Monounsaturated Fat: 7 g | Sodium: 908 mg | Potassium: 550 mg | Fiber: 5 gSugar: 17 g | Vitamin A: 192 IU | Vitamin C: 214 mg | Calcium: 62 mg | Iron: 2 mg