Prep the vegetables before you begin cooking. In a large skillet (12-inch or cast iron), heat about 1 tablespoon of olive oil over medium heat. Once warm, sauté the bell peppers and onion until tender. Transfer to a mixing bowl and set aside.

Add the mushrooms to the skillet, adding a bit more oil if needed. Let them cook undisturbed for a few minutes to brown, then stir occasionally as they continue to soften.

Return the peppers and onions to the skillet, then season with chili powder, paprika, cumin, garlic powder, salt, and pepper. Remove from heat. Warm the tortillas on the stovetop or in the microwave.

To assemble, spoon the mushroom filling into each tortilla, then top with pickled red onion and a squeeze of fresh lime juice.