Whisk together oil, soy sauce, cumin, chili powder, and garlic in a small bowl.
Place portobellos, peppers, and onion in a large bowl. Pour oil mixture over top, then mix well.
Spread veggies on baking sheets in a single layer. Roast for 15 minutes, then flip and cook for another 10 to 15 minutes, or until tender and browned.
Remove veggies from oven and season to taste with salt.
Prepare Guacamole:
While vegetables cook, cut avocados in half, remove pits, and scoop the flesh into a medium bowl.
Lightly mash the avocado, then stir in lime juice and garlic.
Season generously with salt and hot sauce to taste. Cover and set aside.
Prepare Halloumi:
After making guacamole, cut halloumi in half lengthwise, then cut each half into 12 pieces. (You should have 24 pieces total.)
Heat olive oil in a large frying pan over medium heat.
When oil is hot, add halloumi, then cook until lightly browned on bottom. Flip and cook until golden on other side. (You will probably need to do this in batches.)
Serving the Fajitas:
Wrap 4 tortillas in a paper towel and microwave until hot (about 30 seconds). Repeat process with remaining tortillas.
To eat, top tortillas with roasted veggies, halloumi, and your choice of toppings. Serve with a lime wedge. Enjoy!
Notes
This recipe makes 12 fajitas. Assuming most people will eat 2 to 3 fajitas, it should serve 4 to 6 people.You can use either flour or corn tortillas for serving. For a gluten free option, use corn tortillas and replace the soy sauce with tamari.Make sure to read everything before this recipe card for tons of tips, topping ideas, and serving suggestions!