Prepare the mushrooms: If using King Oyster mushrooms, shred them lengthwise using a fork to create a stringy texture. If using Portobello mushrooms, slice them thinly against the grain.
Make the marinade: In a medium bowl, whisk together the olive oil, lemon juice, minced garlic, smoked paprika, cumin, coriander, turmeric, cinnamon, cayenne pepper (if using), salt, and black pepper.
Marinate the mushrooms: Add the prepared mushrooms to the marinade. Toss well to coat every piece. Cover the bowl and refrigerate for at least 30 minutes, or up to 4 hours for deeper flavor.
Cook the mushrooms: Heat a large skillet or grill pan over medium-high heat. Add the marinated mushrooms in a single layer (work in batches if necessary to avoid crowding). Cook for 5 to 7 minutes per side, until the edges are browned and slightly crispy.
Warm the pita bread: Heat the pita bread on a dry skillet or in the oven until soft and pliable.
Assemble the shawarma: Place a portion of the cooked mushrooms onto the warm pita bread. Top with vegan tahini sauce, chopped tomatoes, sliced onions, and fresh parsley.
Fold or roll the pita bread and serve immediately.
Notes
King Oyster mushrooms provide a texture closer to shredded meat, while Portobello mushrooms offer a richer, earthier flavor.
For grilling, thread the marinated mushroom slices onto skewers before cooking over medium heat.
You can make a simple vegan garlic sauce by mixing vegan mayonnaise with lemon juice, minced garlic, and a pinch of salt.