Heat 2 tablespoons oil in large cast iron skillet or heavy pan over medium-high.
Add mushrooms in single layer; cook undisturbed 4-5 minutes until golden brown underneath. Stir; cook another 3-4 minutes.
Push mushrooms aside; add remaining 1 tablespoon oil. Cook peppers and onions 5-6 minutes until softened and charred in spots.
Add chickpeas, chili powder, cumin, paprika, garlic powder, and salt; stir together and cook 2-3 minutes until chickpeas warm through and spices are fragrant.
Warm tortillas in dry skillet or microwave wrapped in damp towel.
Serve filling in warm tortillas with preferred toppings.