Prepare Ingredients: Clean and slice the mushrooms, peppers, and onion. Keep them evenly sliced for consistent cooking.
Heat Skillet: Warm a large skillet (preferably cast-iron) over medium-high heat. Add olive oil and swirl to coat.
Cook Vegetables: Sauté the onions and peppers for 5–7 minutes until slightly softened. Remove and set aside.
Cook Mushrooms: In the same skillet, add mushrooms. Cook for 5–6 minutes until they release their moisture and start to caramelize.
Season: Return the onions and peppers to the skillet with the mushrooms. Add chili powder, cumin, smoked paprika, garlic powder, salt, and pepper. Stir well.
Finish with Lime Juice: Drizzle lime juice over the mixture for a zesty kick. Toss to combine.
Warm Tortillas: Heat tortillas in a dry skillet or microwave until warm.
Assemble Fajitas: Serve the mushroom mixture in tortillas and add your favorite toppings.