Start your Spark and set to 600°F. While the grill preheats, prep the Arais: chop the onion, garlic, parsley, and cilantro as fine as you can.
In a bowl mix all the ingredients together: sirloin, lamb, onion, garlic, parsley, coriander, cumin, Baharat, black pepper and salt, and the pistachios. Leave the olive oil aside. Mix well until homogenous.
Cut the pitas in half. Fill them up with the meat mixture, making sure you spread the meat evenly into the pita. If you like your meat more to the rare side- fill the pita with a thick layer of meat. If you want it well done- spread a thinner layer.
When you are ready to start grilling your Arais, gently brush the grill grates with oil. Lightly brush the pitas with olive oil and place them on the grill. Close the grill and let the pita cook for 4-5 min.
Open the grill, flip the Arais to the other side and cook for another 4-5 min. Close the grill when cooking.
Lastly, grill the open side of the Arais to create a good caramelization on the meat. Serve immediately with a tahini dip.