Heat the vegetable oil in a large skillet or wok over high heat.
Add the thinly sliced beef or lamb and stir-fry for a few minutes until it starts to brown.
Add the sliced onions and green peppers. Continue to stir-fry for another 2-3 minutes until the vegetables begin to soften.
Stir in the diced tomatoes and minced garlic. Cook for an additional 2-3 minutes.
Season the mixture with ground cumin, paprika, salt, and black pepper. Continue cooking until the meat is cooked to your desired level of doneness.
In a small bowl, mix together the tomato paste, pomegranate molasses (if using), red pepper flakes, and salt. Adjust the spiciness to your liking.
Warm the flatbreads on a griddle or in a dry skillet for a few seconds on each side until they become pliable.
Lay a flatbread on a clean surface. Place a lettuce leaf in the center.
Spoon a generous amount of the Tantuni filling over the lettuce.
Drizzle the Tantuni sauce over the filling.
Sprinkle with fresh parsley leaves and a squeeze of lemon juice.
Carefully fold in the sides of the flatbread and then roll it up tightly.
Repeat the process for the remaining flatbreads and filling.
Serve your homemade Tantuni immediately.