Preheat the griddle to medium heat for a few minutes. Add some cooking oil, the red pepper, onion, and mushrooms. Cook 3 to 4 minutes, mixing together with hibachi spatulas.
Add the spinach, garlic, kosher salt, pepper, crushed red pepper flakes, and oregano. Cook 3 to 4 more minutes.
During the last minute put the naan bread on an empty space of the griddle to warm them and mix in the lemon juice or balsamic vinegar with the veggies.
Serve the veggie naan bread tacos with optional toppings such as hummus, feta cheese, and basil.Note: I added hummus to the Naan bread, then added the veggies, feta, and basil.