Heat the olive oil in a large skillet over medium heat.
Add the onion and pepper.
Cook for 2-3 minutes, stirring occasionally.
Add garlic. Stir and cook another 2-3 minutes.
Add sliced mushrooms, garlic powder, chili powder, salt, cumin and broth.
Stir to combine and cook until mushrooms are tender and all liquid has cooked out of the pan.
Use to fill your favorite taco shells. Top with cheese, avocado and any other toppings you like.