In a large bowl make a marinade using the taco seasoning, olive oil and lime juice.
Toss the portobello mushrooms in the marinade until evenly coated.
Spread ingredients across an oiled baking pan and bake for 20 minutes. If you want to add some char to the mushrooms and veggies, broil for another 3 minutes.
Serve with warm tortillas, salsa, guacamole, avocado, and fresh cilantro.