Heat two tablespoons of olive oil in a large skillet over medium heat.
Add the chopped onion and cook, stirring occasionally, until the onion is caramelized and golden brown, about 10-15 minutes.
Allow the caramelized onion to cool slightly before adding it to the meat.
In a large bowl, mix all the filling ingredients until well incorporated. Cover the bowl tightly with plastic wrap and let the mixture rest in the refrigerator for an hour up to overnight.
Stuff the beef mixture into the pita pockets, dividing evenly for 6 Arayes. Press it down to ensure it's well-packed.