Remove the stems and gills from the portobello mushrooms
In a baking dish, marinade the mushrooms in the orange juice, soy sauce, spices, and fresh thyme for 5 minutes or up to two hours.
Turn the mushrooms upside down and fill the caps with the remaining marinade (see photo for reference). Roast for 15 minutes.
While the mushrooms are roasting, sauté the onion and bell pepper in a tablespoon of oil.
After the mushrooms have finished roasting, slice into thin strips and add the mushrooms into the pan with the onion and bell pepper. Continue to sauté until the onions have caramelized slightly.
Lastly, warm your tortillas and build your tacos. I did flour tortillas and shredded cabbage and guacamole with the fajitas but you can use any tortilla to make this gluten free.
Enjoy!
Notes
This makes 4 large tacos or 6 regular sized tacos.